Download The Implications of PGD in the Halakhic and

The Implications of PGD in the Halakhic and Secular Spheres
Can we use modern technology to change our genetic fate?
Shira Levie
Preimplantation genetic diagnosis is one of the most revolutionary medical
advances in recent years. It has altered the way people view the risk of conceiving
children with birth defects. Preimplantation genetic diagnosis (PGD) is an early form
of genetic testing where genetic defects in embryos, conceived through in vitro
fertilization, are analyzed before implantation in the uterus. This offers couples at risk
of genetic diseases the chance to have a healthy child, without facing termination of
pregnancy.1 The Oxford University Press Medical Dictionary expands on this
definition adding that PGD is prenatal genetic diagnosis, extended into the earliest
stages of embryonic development, before implantation occurs. This definition only
scrapes the surface of PGD and the implications that come along with it. To fully
understand the scientific, as well as ethical problems that arise in PGD, it is necessary
to examine every stage and facet involved in preimplantation genetic screening.
The first step in developing preimplantation genetic testing began in 1968. It
was that year that researchers Robert Edwards and David Gardner first reported the
success of sexing rabbit embryos. This marked an important step in the process of
developing preimplantation genetic diagnosis. Scientists were then able to slowly
grasp how to obtain information from the genetic makeup of certain embryos.2 Ten
years later, with the development of in vitro fertilization, PGD took on a new role.
Sermon K. Current concepts in Preimplantation genetic diagnosis (PGD): a
molecular biologist's view. Hum Reprod Update 2002;22:312-8.
2
Harper JC. Introduction. In: Harper JC, Delhanty JDA, Handyside AH, eds.
Preimplantation Genetic Diagnosis. London, UK: John Wiley & Sons; 2001:3-12.
1
This new technology was embraced by the medical community, allowing prospective
parents to select genetically healthy embryos for implantation.
Through these new technologies, the field of preimplantation genetics has
grown tremendously. As of 2006, more than 15,000 PGD cycles had been reported.3
PGD is currently available for most known genetic mutations, such as Aneuploidies,
Cystic fibrosis, Hemophilia A and B,and Tay Sachs disease.4 Since only unaffected
embryos are selected through PGD to be implanted to the uterus it provides a
preferable alternative to current prenatal diagnostic procedures which occurs at the
beginning of pregnancy and can be performed as late as nine weeks into the
pregnancy.5 Since the baby is already beginning to form by this stage of the
pregnancy, the test is frequently followed by the difficult decision of pregnancy
termination if the results indicate an unhealthy fetus. Additionally, prenatal testing
results an 8% higher spontaneous miscarriage possibility then on those fetuses not
tested. 6
Since preimplantation genetic diagnosis tests are done on embryos resulting
from in vitro fertilization and only the healthy ones are implanted, it avoids the issue
of termination of pregnancy. With these advantages, this new method has quickly
gained popularity among prospective parents. While this technique is widely accepted
and many depend on its results, there is still a long way to go for PGD. Reports of the
identification of genetic changes linked to various diseases are published almost
3
SART CORS Web site. Available at https://www.sartcorsonline.com/.
International Working Group on Preimplantation Genetics, International Congress of
Human Genetics.Preimplantation Genetic Diagnosis: Experience of Three Thousand
Cycles. Report of the 11th Annual Meeting of International Working Group on
Preimplantation Genetics, in association with 10th International Congress of Human
Genetics. Vienna, Austria: May 2001:[Full Text].
5
Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review). By
Alfirevic Z, Mujezinovic F, Sundberg K at The Cochrane Collaboration, 2009
6
ibid
4
weekly.7 Scientists are constantly working to improve the accuracy of these tests and
the techniques used to obtain the results.
The main attraction of preimplantation genetics to prospective parents is the
prevention of birth defects in their offspring. For all pregnancies, the baseline risk of
some type of birth defect is 3 to 4%.8 Since the severity of such defects varies widely
as a result of inheritance, occurrence of spontaneous mutations, and environmental
influence, it is hard to pinpoint a set of guidelines for couples in order to justify
having PGD preformed on their embryo.9 One type of couple that would be a
candidate for PGD testing is a couple that has a history of known genetic conditions
in their immidiate family or who have given birth to a child with a genetic disorder.
This could be a disease caused by a single gene defect, a monogenic disease, or
chromosomal abnormality in the offspring, due to a balanced chromosomal
rearrangement in one of the partners. These types of couples are offered guidance by
The American Congress of Obstetricians and Gynecologists (ACOG.) It recommends
that women be offered information about genetic risks, and therefore can decide if
they should test their embryos using PGD. 10
While couples who have previous experience within their immediate family
with genetic defects are more inclined to use PGD, a family history of genetic
disorders is not required for genetic screening. Genetic testing may be carried out
when there is suspicion that an individual is at increased risk because of extended
7
Molina B Dayal, MD, MPH Associate Professor, Medical Director of Egg
Donation Program, Department of Obstetrics and Gynecology, Division of
Reproductive Endocrinology and Infertility, Medical Faculty Associates, George
Washington University School of Medicine
8
McKusick–Nathans Institute of Genetic Medicine, Johns Hopkins Medical
Institutions, Baltimore; Department of Obstetrics and Gynecology
9
McKusick–Nathans Institute of Genetic Medicine, Johns Hopkins Medical
Institutions, Baltimore; Department of Obstetrics and Gynecology
10
Ibid
family history or because of a positive result on a biochemical screening test.11
Additionally, some couples use this technology for social reasons in order to select
gender and other social traits. While not recommended, this is an unfortunate reality
of this new technology. This has sparked an ethical debate within the medical
community.
Preimplantation genetic diagnosis can be carried out at different stages of
embryonic development. There are three methods that can be used to obtain genetic
material in order to test for a deficiency in a potential embryo. All three methods
have pros and cons and each methodology utilizes a different stage of the embryonic
development.
The process of egg production, called oogenesis, begins in the female fetus.
Each woman is born with a certain number of cells capable of becoming an egg.
These cells go through oogenesis to produce oocytes. After maturing, the oocyte
divides into two new cells of unequal size: a relatively large oocyte and a minute
polar body. A second stage of division occurs which produces a second polar body
and a large ootid (mature egg cell.) All cells contain the maternal DNA, but the polar
bodies eventually die leaving the mature egg cell to be fertilized. When an egg is
fertilized by a sperm cell it creates a zygote containing half of the genetic information
from each parent. This zygote then undergoes the cleavage stage where it divides
rapidly, first becoming a ball containing four cells, then an eight cell ball called the
cleavage stage. After many more rounds of cell division the developing embryo
becomes a blastomere containing hundreds of cells. The process continues and the
cells divide forming organs and limbs, and ultimately a child.
11
Ibid
The first method for carrying out PGD examines the genetic material within
the polar bodies, the by-products of the first and second stages of division.12 These
cells are exclusively made up of the mother’s DNA. This method can be used in case
of maternally derived dominant mutations, aneuploidy and translocations which are
chromosome defects caused by the rearrangements of parts between non similar pairs
of DNA. The first and second polar bodies can be analyzed to determine the presence
of maternal genetic contributions (i.e., X-linked diseases and autosomal dominant
diseases), including carrier states for Duchenne's muscular dystrophy, incontinentia
pigmenti, and neurofibromatosis type. 13
While this method is advantageous as the polar bodies are considered a waste
of nuclear material after meiotic division and do not have any physiological role to
play in the development of embryos, it does present some difficulties. The polar
bodies cannot be used when paternally derived genetic information is critical for the
diagnosis, such as paternally derived mutations, translocations, and aneuploidy.14
Additionally this technique presents a problem as many chromosomal abnormalities
arise after fertilization. Polar body testing can prove to be inaccurate regarding the
actual health of the baby. Nevertheless, it is a widely accepted practice to screen for
diseases as it yields improved pregnancy outcomes by detecting maternal genetic
abnormalities in eggs, including meiotic errors that result in aneuploidy.
The most widely used approach for obtaining genetic material is testing the
individual embryonic cells from the cleavage state of the embryo. These cells, called
blastomeres, are obtained on the third day after in vitro fertilization and are removed
12
Adiga S K, Kalthur G, Kumar P, Girisha K M. Preimplantation diagnosis of genetic
diseases. J Postgrad Med 2010;56:317-20
13
McKusick–Nathans Institute of Genetic Medicine, Johns Hopkins Medical
Institutions, Baltimore Department of Obstetrics and Gynecology
14
Adiga S K, Kalthur G, Kumar P, Girisha K M. Preimplantation diagnosis of genetic
diseases. J Postgrad Med 2010;56:317-20
through a hole created in the zona pellucida,15 the strong membrane that forms around
an ovum as it develops in the ovary. After testing, the embryos can be transferred into
the uterus on day four or five. This allows enough time for genetic analysis to be
performed and for the implantation of genetically normal embryos, which have now
progressed through the blastocyst stage.16 The advantage of this method is that it
contains both the maternal and paternal genes. However, it must be taken into
consideration that there is a limited amount of cells available for use in this stage.
That can limit the accuracy of results as well as the development of the fetus.
Another approach is to use the non-embryo forming cells (trophoectoderm
cells) of the embryos on day 5 of development.17 In this case, the cells that are taken
will not become part of the baby, rather they will grow into what will become the
placenta. The main advantage of this method is that many cells are available to be
genetically analyzed, unlike the blastomere biopsy, where very few cells are available.
These cells also are obtained by the culturing of the zygote until they reach the
blastocyst stage and then Zona drilling to remove cells that can be used for biopsy.
The major limitation of this approach is the requirement that a sufficient number of
embryos reach the blastocyst stage in vitro, thus giving a sufficient number of cells.
There is a very brief opportunity for genetic assessment at this stage as the embryos
need to be implanted quickly after assessment. 18 This time constraint leaves a very
small window for testing and can prove to be inaccurate. Lastly, the TE cells may not
reflect the true genetic features of the cells.
15
Adiga S K, Kalthur G, Kumar P, Girisha K M. Preimplantation diagnosis of genetic
diseases. J Postgrad Med 2010;56:317-20
16
Ibid
17
Ibid
18
Adiga S K, Kalthur G, Kumar P, Girisha K M. Preimplantation diagnosis of genetic
diseases. J Postgrad Med 2010;56:317-20
After the polar bodies or cells are obtained, there are different methods that
are used for screening for genetic abnormalities. Each screening involves tests for the
most common mutations and specific diseases in particular populations.19 The three
methods that are commonly used to carry out testing are polymerase Chain reaction
(PCR), fluorescence in situ hybridization (FISH), and single-nucleotide
polymorphism (SNP.) The screening method employed will depend on the type of
genetic disorder suspected based on the knowledge of each specific case. In all cases
the embryo's health is not effected by the tests if preformed correctly.
Polymerase Chain Reaction (PCR.) is used for the diagnosis of single gene
defects. This test has a 97% accuracy rate, making it a fairly reliable diagnostic test.20
Recent advances in DNA sequencing and bioinformatics have led to an approach that
identifies carriers of known mutations that cause more than 400 recessive genetic
diseases. These include both dominant and recessive disorders such as cystic fibrosis,
spinal muscular atrophy, myotonic dystrophy, Huntington disease, and Marfan
syndrome. This test makes many copies of the region of interest in the DNA of a
biopsied cell, allowing scientists to study the DNA and determine the health of the
selected embryo. In this test, the DNA is immersed in a solution containing the DNA
polymerase enzyme, unattached nucleotide bases, and primers. The solution is heated
to break the bonds between the strands of the DNA. When the solution cools, the
primers bind to the separated strands, and the DNA polymerase quickly builds new
strands by joining the free nucleotide bases to the primers. Further repetitions of the
19
McKusick–Nathans Institute of Genetic Medicine, Johns Hopkins Medical
Institutions, Baltimore Department of Obstetrics and Gynecology
20
Munne S, Sandalinas M, Escudero T, Velilla E, Walmsley R, Sadowy S, et al.
Improved implantation after preimplantation genetic diagnosis of aneuploidy. Reprod
Biomed Online.2003;7:91–97.
process can produce billions of copies of a small piece of DNA in several hours.21
This test can be performed on a polar body, cleavage, or TE cell.
PCR is a fast and convenient way to test DNA. However, it requires sufficient
amounts of an uncontaminated, high-quality sample of DNA, which is sometimes
difficult to obtain from a single cell such as a polar body or blastomere. The
laboratory in which PCR is being carried out must be strictly controlled to avoid the
contamination of the tested material. The laboratory technicians must be exceptionally
well-trained to avoid all types of foreign, interfering factors. In addition, allele
dropout is a serious complication. The phenomenon known as allele dropout presents
one of the most common problems for PCR.22 Both cleavage cells and balstomeres
contain two copies of every gene, each called an allele. Either one or both of the
alleles may be defective. Allele dropout refers to the preferential amplification of one
allele over another during the PCR process and is mainly a problem for PGD of
dominant disorders or when two different mutations are carried for a recessive
disorder and only one mutation is being analyzed. Therefore, all of the possible
genetic makeups of the embryonic cells are not represented. This results in a 3%
likelihood of inaccuracy.
These inaccuracies in PCR can result in misdiagnoses, harming embryos as
they are handled or the discarding of a normal embryo. This risk of using PCR is
easily overlooked as the success rate is so high. It may be noted however that a polar
body contains a single copy of the DNA (haploid) and the cell biopsied at all other
21
Treff NR, Tao X, Lonczak A, Su J, Taylor D, Scott RT., Jr Four hour 24
chromosome aneuploidy screening using high throughput PCR SNP allele ratio
analyses. Fertil Steril. 2009
22
Scott RT, Jr, Tao X, Taylor D, Ferry K, Treff N. A prospective randomized
controlled trial demonstrating significantly increased clinical pregnancy rates
following 24 chromosome aneuploidy screening: biopsy and analysis on day 5 with
fresh transfer. Fertil Steril. 2010
stages have double copies of the DNA (diploid). Therefore using a polar body is
difficult for PCR, as only a single cell is the source of DNA.23 The DNA must be
amplified many times in order to have enough material to analyze. Taking that into
consideration, as well as the issue of allele dropout, PCR is still a very accurate way
of testing and many doctors turn to this method as a way to detect mutation.
Fluorescence in situ hybridization (FISH) is another method used in PGD.
FISH is used for the determination of chromosomal abnormalities such as aneuploidy
and the sex of an embryo to better diagnose X-linked diseases. Aneuploidy refers to
an abnormal number of chromosomes, which causes birth defects such as down
syndrome. Aneuploidy screening is by far the most common indication for PGD.
Since an abnormal chromosome number can be the cause of low sucess in implanting
embryos as well as recurring miscarriges of unidentified causes, PGD has been used
to increase the success rate of full term pregnancies.24
The way FISH is carried out is by using probes (ie, small fragments of DNA
that match the chromosomes being analyzed) and binding them to a certain
chromosome. Each probe is labeled with a different fluorescent dye. These
fluorescent probes are applied to the cell biopsy sample and attach to the specific
chromosomes. They can be observed under a fluorescent microscope. The number of
chromosomes of each type (color) present in that cell is counted. The geneticist can
then distinguish normal cells from abnormal cells. The common probes are used to
detect abnormal chromosomes for chromosomes X, Y, 13, 18, and 21. The number of
chromosomes tested in a single FISH is limited by the number of fluorescent probed
23
Adiga S K, Kalthur G, Kumar P, Girisha K M. Preimplantation diagnosis of genetic
diseases. J Postgrad Med 2010;56:317-20
24
Adiga S K, Kalthur G, Kumar P, Girisha K M. Preimplantation diagnosis of genetic
diseases. J Postgrad Med 2010;56:317-20
available. However, mixing of colors, several rounds of FISH on the same cell, and
comparative genomic hybridization (CGH), enhance the possibility of detecting the
abnormalities in several chromosomes/regions.25
One of the key limitations of FISH based preimplantation aneuploidy
screening is the inability to simultaneously evaluate all 24 chromosomes found in
human cells (chromosome 1–22, X and Y).This limits the number of irregularities that
FISH can screen for. FISH would not be the preferred mode of testing if all
chromosomes need to be analyzed. Additionally, in an evaluation of FISH, results
were obtained indicating that FISH gives inconsistent results.26 However, FISH offers
accurate results in detecting Aneuploidy screening in women of advanced maternal
age, aneuploidy screening for male infertility, identification of sex in X-linked
diseases, and recurrent miscarriages caused by parental translocations. FISH can be
used for these detections in which it is accurate.
When FISH is the screening technique used, false results may be generated by
failure of the probes to hybridize, poor signal intensity, split or fused signals. As only
a single cell is analyzed, mosaicism, the evidence that mosaic embryos are able to
stop the reproduction of abnormal cells and continue to develop into a healthy
embryo, is not accurately detected by this technique. Mosaicism poses a problem to
PGD as it can obtain false results and cause the discarding of many healthy embryos.
This is especially important, as there may be a trisomy rescue and embryos that are
diagnosed to have a trisomy may eventually develop into a fetus with normal
chromosomal content. It is estimated that misdiagnosis in aneuploidy screening after
25
Adiga S K, Kalthur G, Kumar P, Girisha K M. Preimplantation diagnosis of genetic
diseases. J Postgrad Med 2010;56:317-20
26
Fiegler H, Geigl JB, Langer S, Rigler D, Porter K, Unger K, et al. High resolution
array-CGH analysis of single cells. Nucleic Acids Res. 2007;
the biopsy of one blastomere is 7%, with 6% due to mosaicism. 27 Mosaicism is the
idea that many embryos identified as aneuploid will survive and return to normal after
correcting the defect in a cell.28 As there is a high level of chromosomal mosaicism in
the cleavage stages of embryonic development, which can confound the interpretation
of data or demand follow-up analysis, and because contemporary FISH methods do
not capture the full complement of chromosome material, the extent to which
preimplantation genetic screening is useful in improving pregnancy rates and
outcomes is debated.29 This is a downside to this testing as the embryo can correct
itself, causing the discarding of potentially healthy embryos. This also provides the
risk of false test results in a circumstance in which one cell in the embryo is healthy
and the rest are defective, and the healthy one is tested, then false results about the
health of the embryo will be obtained.
The most recent developments in Preimplantation genetics has created a new
screening process using single nucleotide polymorphisms, or SNPs. These are DNA
sequence variations that occur when a single nucleotide in a strand of DNA is altered.
According to the Human Genome Project for a variation to be considered a SNP, it
must occur in at least 1% of the population. SNPs, which make up about 90% of all
human genetic variation, occur every 100 to 300 bases along the 3-billion-base human
genome. SNPs can occur in coding (gene) and noncoding regions of the genome.
Many SNPs have no effect on cell function, but they have been correlated with an
27
Munné S, Magli C, Bahçe M, Fung J, Legator M, Morrison L, et al. Preimplantation
diagnosis of the aneuploidies most commonly found in spontaneous abortions and live
births: X, Y, 13, 14, 15, 16, 18, 21, 22. Prenat Diagn 1998;18:1459-66
28
Rius M, Daina G, Obradors A, Ramos L, Velilla E, Fernández S, et al.
Comprehensive embryo analysis of advanced maternal age–related aneuploidies and
mosaicism by short comparative genomic hybridization. Fertil Steril. 2011
29
McKusick–Nathans Institute of Genetic Medicine, Johns Hopkins Medical
Institutions, Baltimore Department of Obstetrics and Gynecology
increased probability of developing diseases such as diabetes, vascular disease, and
some forms of mental illness. These associations are difficult to establish with
conventional gene-hunting methods because a single altered gene may make only a
small contribution to the disease.
In order to test for these SNP’s high-density oligonucleotide, SNP arrays are
used. In this form of testing, hundreds of thousands of probes of DNA from a zygote
are arrayed on a small chip, allowing for many SNPs to be investigated
simultaneously. Because SNP alleles only differ in one nucleotide and because it is
difficult to achieve optimal hybridization conditions for all probes on the array, the
target DNA has the potential to hybridize to mismatched probes. This is addressed
somewhat by using several unnecessary probes to hybridize to each SNP. By
comparing the differential amount of hybridization of the target DNA to each of these
probes, it is possible to determine specific homozygous and heterozygous alleles.
The use of SNP arrays proves to be beneficial in many ways. A study was
done proving that SNP array data is able to detect mosaicism better than the FISH
method. 30 This is very important as mosaicism is a major contributor to the error rate
in PGD. It also may be able to detect aneuploidy among all 24 chromosomes, which
has not been achieved by other methods of testing. While SNP proves to be an
effective and worthy method, it also comes with complications. This type of test is
very expensive and the results may be inconsistent because of overlapping probes that
sometimes are considered independent, presenting errors in the data.31 SNP array
analysis is fairly new to the world of PGD and the technology is still being modified
30
Fiegler H, Geigl JB, Langer S, Rigler D, Porter K, Unger K, et al. High resolution
array-CGH analysis of single cells. Nucleic Acids Res. 2007;
31
Caignec C, Spits C, Sermon K, Rycke M, Thienpont B, Debrock S, et al. Single-cell
chromosomal imbalances detection by array CGH. Nucleic Acids Res. 2006
to be as accurate as possible. It is an alternative to PCR and FISH and is expected to
become the quintessential way of performing PGD in the years to come.
In addition to the limitations pertaining to each test individually, one limitation
that is present for all types of testing is that it is not always possible to predict the
severity of a clinical condition on the basis of a genotype (only the genetic makeup of
the embryo). A laboratory result may be flawless, but the identified genetic variation
may not be known to cause a disease (i.e., it is a variant of uncertain significance).
Alternatively, the discovered mutation or variant in a known disease gene may not
reliably correlate with a phenotype, what actually becomes of the zygote, because of
the influence of modifiers, which can be genetic, epigenetic, or environmental.32 This
can result into the discarding of healthy embryos or the implantation of unhealthy
ones. This presents not only a medical, but also an ethical and religious problem.
Considering the limitations, methods, and results of PGD, one must now
approach this type of test from both an ethical and religious standpoint. When
assessing this problem, it is necessary to be mindful of the views of society as well as
the approaches of the Jewish sages and modern Halakhic authorities. Preimplantation
Genetic Diagnosis presents many dilemmas in modern medical ethics, all which are
considered by Rabbis in order to make decisions. Since Jews marry within their
ethnicity they have a much higher rate of many gene mutations, most notably TaySachs, a lethal disease common in the Ashkenazi Jewish community. Another
common gene in the Jewish community is the BRCA gene, which, when found, is an
early indicator of breast cancer as a woman ages. These genetic mutations cause PGD
to be an emerging topic as many Jewish couples wonder if preimplantation testing is
32
McKusick–Nathans Institute of Genetic Medicine, Johns Hopkins Medical
Institutions, Baltimore Department of Obstetrics and Gynecology
their best option to obtain a healthy embryo. The Rabbis must consider many Jewish
laws when deciding what is halakhically permissible when preforming PGD on an
embryo.
The initial question regarding PGD and halakha is if halakha even permits
PGD for a couple conceiving. As previously mentioned, PGD is a preferred method of
screening over prenatal genetic screening, as it does not present the ethical problem of
termination of pregnancy. The issue of abortion is a charged topic, debated in politics
as well as in religion and medical ethics. On one hand is the issue of the sanctity of
life and the concern for the right to life of the yet unborn. On the other hand,
government regulations of abortion are seen as a violation of privacy and a woman’s
right to choose whether or not to see a pregnancy to term. This dilemma is fueled by
the disagreement over the timeframe that a fetus is considered a life and the power
that a mother has over the life of her potential child.
From the standpoint of Jewish Law, up until forty days, the fetus is considered
maya b’alma (mere water).33 Until the unborn baby’s head emerges, if causing the
mother harm, the fetus is considered a pursuer (rodef). The mother’s life can be
preserved through self-defense even if resulting in fetal death.34 Therefore, abortion
is generally reserved only for cases involving danger to the mother. However, if the
threat is a fetal abnormality, R. Feinstein prohibits abortion and rules that prenatal
birth defect detection with the possibility of abortion is not permissible. He derives
this from the source in the Seven Laws of Noah which states cases of capital
homicide. The Talmud’s rendition of Genesis 9:5, which describes the prohibition of
killing says “if a person shed the blood if a man within a man, he shall be killed.” the
33
34
Yevamot 69b, Nida 30a, Rashi Nidda 30a Talmud Bavli
Mishnah ohalot 7:6
Talmud proceeds to ask, “and who is a man within a man? This is the fetus within the
womb of the mother,” This verse thus prohibits the killing of a fetus within the
mother, ruling that abortion is prohibited on a biblical level. Most halakhic authorities
agree on this ruling.
If abortion is not permitted, a question then arises regarding whether one is
able to discard the embryos that were created but deemed unhealthy to implant by
way of FISH, SNP, or PCR. The Jewish debate over this matter is fueled by the
forbidding of one to waste potential life, as stated in Gen. 38:9-10 “Zera Levatala.”
35
Judaism sees much value in every potential life, extending to not wasting sperm.
What does this come to imply about PGD and discarding affected embryos? While
allowing IVF, Rabbi Feinstein prohibits embryo discarding in this situation, since it
eliminates potential life. However, many other Rabbis such as Rabbi Lichtenstein
disagree, because producing healthy children is intended through consideration of
parental anguish. The Committee on Medical Ethics of the Federation of Jewish
Philanthropies of New York concluded that as the embryo was in a test tube
environment in which viability is unattainable, it is not considered human life and can
be discarded.36 This is because it is not in a setting where it can flourish and become a
human, therefore, since removed from the uterus, it is not considered a potential life.
With most Rabbis agreeing that it is halakhically permissible to discard
defective embryos, thus deeming the actual tests halakhically permitted, it is
necessary to explore if the test’s aims are permitted by halakha. One could challenge
whether it is the place of man to intervene and assert control in God’s world. Is man
35
Genesis 38:9-10, Rashi Genesis 38:7, supra, note 56; Rambam, Hilchot Issurei Biah
21:18, supra, note 22; Niddah 13a, 13b, supra, note 21
36
Feldman, D. M. & Rosner, F. (1984). Compendium on Medical Ethics. New York:
Federation of Jewish Philanthropies of New York, 28
allowed to interfere with nature and create a genetically modified human? From a
secular ethical standpoint,the problem is widely debated and is the source of a set of
codes established by the Human Fertilization Embryology Authority, or HFEA, in the
United Kingdom. They establish a set of certain diseases and chromosomal
abnormalities that an embryo can be screened for, thus instituting guidelines for the
extent to which man can play a role in the making of nature’s creation. These codes
proved controversial, as many passionately advocated for one extreme or the other,
namely, that PGD should always, or never be allowed. This debate, in the secular
world, is about interfering with nature. From the Jewish perspective, one is not only
tampering with nature, but with God.
The Jewish world was shaken by the introduction of PGD, as the question of
playing God became a cause célèbre. There is the belief that mankind should play its
part in God’s plan, using world resources to continue God’s creation according to the
law of tikun olam; healing the world.37 Therefore, we allow physicians to practice
and heal, though they are intervening with God’s hand in the health of man. 38
However, a medical procedure that presents no chance of healing violates the Jewish
decree against tampering with God’s creation. PGD does not heal, it merely chooses
one embryo over another and, therefore, is a valid basis for a Jewish prohibition.
There seems to be a lack of halakhic consensus in this area. Many authorities are yet
to come to a conclusive ruling, however, consideration of the issues individually
assists many Rabbis in deciding whether PGD is halakhically permissible.
37
Genesis 1:26, supra, note 56; Buber, S. (1925). Midrash Shemuel. Vilna: Romm,
section 4
38
Sh’mot, 21:18-9, Vayikra 19:16, Devarim 22:1,3, supra, note 56; Bava Kama 85a;
Brakhot 60a; Sanhedrin 73a; supra, note 21 Shulkhan Arukh, Yoreh Deah, 336:1, in
Steinberg, A. & Rosner, F. (2003) Encyclopedia of Jewish Medical Ethics. Jerusalem:
Feldheim, 101
Many Poskim maintain that one can perform genetic testing if the embryo has
a ‘serious or significant’ defect. This makes it the job of the Rabbis to decide what is
considered worthy of us interfering with God’s plan. The World Health Organization
originally defined serious disease in terms of etiology and process, into which
disability was subsumed causing impairments, disabilities, and handicap. This would
come to include the lethal disease Tay- Sachs. An alternative definition to a ‘serious
condition’ used by many contemporary social organizations is that it is the
disadvantage of restriction that excludes them from mainstream social activities. This
may include Trisomy 21, or the detection of the BRCA gene. The practical difference
between these two definitions is that according to the World Health Organization the
embryo should only be prevented from being implanted if the child will have a
mutation causing severe physical and mental disabilities, lessening quality of life, or
in extreme cases, death. In contrast, according to the definition used by many social
organizations, if an embryo has any sort of defect that might slightly impair quality of
life in some way, the embryo should not be implanted.
Should ‘serious’ or ‘significant’ be the criteria used by Poskim? It is difficult
to draw a non-arbitrary line between severe and non-severe, it being dependent on the
circumstances and dogma. One thing to consider is that Judaism believes in the
sanctity of life and upholds the belief that each person is created in God’s image. Each
person has spiritual value, regardless of their abilities or lack thereof. There is even a
blessing that many say upon seeing a deformed person. The Talmud addresses people
with disabilities asking, ‘do you think your blood is redder than his? Perhaps his is
redder than yours!,’39 which serves to remind how judgments are made on
externalities, lacking knowledge of individuals' true value. Therefore, it is
39
Pesakhim 25b, supra, note 21
questionable as to whether a Rabbi can tell a couple that they can perform PGD,
therefore preventing the creation of a mutated child, God's creation.
This being considered, it must also be noted that the disabled are excluded
from the performance of several mitzvot due to lack of required functionality,40 as one
can deduce that PGD is allowed according to halakha in order to maximize the
contributions of a Jew into the halakhic world. This can eliminate the line that needs
to be drawn between serious and less serious cases, using the potential impairment to
participate in Halakha as a way to determine whether or not to implant the embryo.
This is supported by Rabbi Yosef Shalom Eliyashuv, an influential posek in Israel
today, who has permitted pre-implantation diagnosis on the basis that it is allowed by
Halakha.
If PGD is indeed halakhically permissible, the debate arises whether or not it
is required to test embryos by way of PGD by the Torah obligation to guard his
health. One must distinguish if this law is extended to mean to guard his health, and
the health of the child he will create. Rabbi Moshe Feinstein favored Tay-Sachs
testing and considered the possibility that testing might be a moral obligation. He
states that while one may usually ignore a small risk that society finds acceptable not
being tested for a disease that can be life threatening is like closing one's eyes to an
obvious danger, something that is directly prohibited by the Torah. Therefore, one can
conclude that a couple has a moral as well as a religious obligation to use PGD to test
for lethal diseases. The extent to which these tests can be used varies.
Preimplantation Genetic diagnosis is a revolution in the medical world. Its
potenail uses and benefits continue to be developed. However, considering the many
methods used to carry out PGD as well as its limitations and error rates there are
40
Outlined in Marx, T. (1993). Thesis: Halakha and Handicap: Jewish Law and
Ethics on Disability. Jerusalem: Marx, T.
many ethical and religious debates about this new technology. Both in religion and
secular ethics, there is no one correct answer as to what extent this technology can be
used. In religion, while it does vary by individual case, many influential rabbis agree
that PGD is Halakhicly permissible based on many Talmudic and Torah references.
This being said it cannot be abused to include social traits that will not affect a
person’s contribution to the world of Judaism. PGD, though one of the most
controversial medical developments, is an incredibly significant resource for the
future of medicine. As it progresses, PGD will become more accurate and inexpensive
and ultimately has tremendous potential to change the world.