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Cat Eye Syndrome
By : Amy C
4th block
Chromosome 22

Chromosome 22 is the second smallest of the
human autosomes. The short arm (22p) contains a
series of tandem repeat structures including the
array of genes that encode the structural RNAs of
the ribosomes, and is highly similar to the short
arms of chromosomes 13, 14, 15 and 21. The long
arm (22q) is the portion of human chromosome 22
that contains the protein coding genes and this is
the region that has now been sequenced. The
completed sequence consisted of 12 contiguous
segments covering 33.4 million bps separated by
11 gaps of known size.
What is Cat Eye Syndrome?

Cat eye syndrome is a rare chromosomal disorder
that may be evident at birth. Individuals with a
normal chromosomal make-up have two 22nd
chromosomes, both of which have a short arm,
known as 22p, and a long arm, called 22q.
However, in individuals with cat eye syndrome, the
short arm and a small region of the long arm of
chromosome 22 (i.e., 22pter-22q11) are present
three or four times (trisomy or tetrasomy) rather
than twice in cells of the body.
Where does Cat Eye Syndrome
come from?

The name "cat eye syndrome" is derived
from a distinctive eye (ocular) abnormality
that is present in some affected individuals.
This feature consists of partial absence of
ocular tissue (coloboma), often affecting
both eyes (bilateral). Affected ocular tissues
may include the colored region (iris), the
middle layer (choroid), and/or the nerverich innermost membrane (retina) of the
eye.
What does Cat Eye Syndrome cause?

Symptoms and findings may vary greatly in range
and severity, including among affected members
of the same family. While some may have few or
mild manifestations that may remain
unrecognized, others may have the full spectrum
of malformations. However, in many cases,
characteristic features of the disorder include mild
growth delays before birth; mild mental
deficiency; and malformations of the skull and
facial (craniofacial) region, the heart, the kidneys,
and/or the anal region.
What are some of the other leading
causes of Cat Eye Syndrome?

Individuals with cat eye syndrome frequently have
coloboma(s), downslanting eyelid folds (palpebral fissures),
widely spaced eyes (ocular hypertelorism), and/or other
ocular defects; misshapen ears with abnormal outgrowths
of skin and small depressions in front of the outer ears
(preauricular tags and pits); and/or absence (atresia) of the
anal canal, with an abnormal passage (fistula) from the
end portion of the large intestine (rectum) into abnormal
locations (e.g., the bladder, vagina, or perineum).
Additional features may commonly include variable
congenital heart (cardiac) defects, kidney (renal)
abnormalities, skeletal defects, and/or other physical
findings.
When was the first case of Cat Eye
Syndrome reported?

The additional chromosome 22 generally arises de
novo from one of the parents. Since CES is a rare
chromosome disorder in which transmission is
possible through both sexes, chromosome
examination should be performed if one of the
parents displays characteristic features such as a
preauricular pit or downslanting palpebral
fissures. Even in nonsymptomatic parents,
mosaicism for an extra chromosome is possible.
The earliest transmission was reported by
Schachenmann et al. (1965)
Related causes of Cat Eye Syndrome

A female with a severe form of CES associated with a
molecular type II chromosome. At birth, she had severe
craniofacial abnormalities, including microcephaly, total
absence of the external ears bilaterally, hypertelorism with
downslanting palpebral fissures, bilateral coloboma of the
iris, flat nasal bridge with prominent nose, thin upper lip,
and micrognathia. Other features included anal stenosis,
patent ductus arteriosus, and intra- and extrahepatic
biliary atresia. She died at age 1 month of cardiac failure.
Cytogenetic analysis showed a small de novo extra
chromosome in all cells with a karyotype of 47,XX,
+idic(22)(pter-q11.2::q11.2-pter) with the duplication
breakpoints distal to 22q11.2. The marker could be
classified as CES type II symmetrical.
Cat Eye Syndrome
 Cat
Eye Syndrome can sometimes be
fatal.
 However, most cases are only a
disorder that a person can live with.
References
www.google.com.12/11/06
 www.chromosomes.com12/12/06
 www.diseases.com12/13/06
 www.galileo.com12/13/06

Putative genes
Genomic structure of genes