Download Tandem Mass Spectrometry

The Expanding Expanded
Newborn Screen
R. A. Heidenreich, MD
Professor of Pediatrics
Division of Pediatric Genetics
The University of New Mexico
Expansion of Testing

Historically, the blood was tested for accumulated products
of abnormal metabolites
– Phenylalanine was the first disorder tested beginning in the 1960s
but slowly more disorders were added


Prior to about 5-10 years ago (depending on which state)
the number of disorders tested for was 4-8
With the technologic advance of tandem mass
spectrometry, the number of disorders able to be assayed
increased significantly.
Mass Spectrometry

Small sample from the original newborn screening
card
 Blood extracted and compounds derivatized to
make more volatile
 Injected into the MS/MS machine, ionized, sent
through varying magnetic fields that separates
molecules based on mass and charge
 Molecule is also fragmented and gives a very
specific detection pattern
March of Dimes and ACMG

Two organizations have attempted to codify a
uniform panel of diseases for newborn screening
– 29 disorders including newborn hearing
– However, because of the ability of MS/MS to detect
even more disease, there is debate about adding even
more disorders

New Mexico is following these recommendations
 However, because of the expense of the
instruments, all samples are sent to Oregon for
analysis
Categories of Disorders

Amino acid disorders
– Phenylketonuria, tyrosinemia, citrullinemia, and
argininosuccinic aciduria

Organic acid disorders
– Maple syrup urine disease, propionic acidemia,
methylmalonic acidemia, fatty acid oxidation disorders

Carbohydrate disorders
– Galactosemia
Categories of Disorders

Vitamin disorders
– Biotinidase deficiency

Endocrine disorders
– Congenital hypothyroidism, congenital adrenal
hyperplasia

Hematologic disorders
– Hemoglobinopathies
• Sickle cell disease

Congenital Deafness
 Cystic Fibrosis
Present Testing Methods

Tandem Mass Spectrometry
– For all of the amino acid and organic acid disorders

Biotinidase
– Colorimetric assay of biotinidase activity

Galactosemia
– Colorimetric assay of galactose-1-phosphate
uridyltransferase activity

Congenital hypothyroidism
– T4 and, if abnormal, TSH levels
Present Testing Methods

CAH
– 17-OH progesterone assay

Hemoglobinopathies
– Hgb electrophoresis

Cystic fibrosis
– Trypsinogen levels
– DNA analysis

Deafness
– Acoustic emissions in the hospital
Disorders

Phenylketonuria
• Classical form
• Mild hyperphenylalaninemia
• Untreated, it causes severe mental retardation, seizures.
Dietary restriction of phenylalanine is a highly effective
treatment and children, if well-treated, are normal.

Tyrosinemia
– Type I most severe and causes severe liver failure in the first
year of life.
– Treatable with Orfadin® (NTBC) and dietary protein restriction
– May still require liver transplantation later in life (increased risk
of hepatic cancer)
Disorders, cont.

Homocystinuria
– Mental retardation, ocular lens dislocation, Marfanoid body
habitus
– Treat with dietary protein restriction

Urea cycle defects: citrullinemia and
argininosuccinic aciduria
– There are other urea cycle defects but testing MS/MS not yet
applicable
– Severe hyperammonemia
– Dietary protein restriction, medications
Disorders, cont.

Organic acidemias
– Maple syrup urine disease
• Very dangerous disorder that presents in the first week of life
• Treat with dietary protein restriction
– Fatty acid oxidation defects
• MCAD is most common and may present with hypoglycemia
and Reye-like symptoms
– Many others:SCAD, LCAD, LCHAD, SCHAD, VLCAD,
carnitine deficiency
• Treat by avoidance of fasting and carnitine supplementation
– Other organic acid disorders
• Propionic, methylmalonic, HMG-CoA lyase, 3-MCC
– Acidosis, seizures
• Treat by dietary protein restriction, alkali therapy and
avoidance of fasting
Disorders, cont.

Biotinidase deficiency
– Causes biotin deficiency beginning at about 4-6 months
of life
– Dermatitis, alopecia, acidosis, neurologic impairment
– Treat with 5-10 mg of biotin a day

Galactosemia
– Hyperbilirubinemia, hepatitis, cataracts, hypoglycemia,
urine reducing substances
– Treat with lactose-restricted diet
Disorders, cont.

Congenital hypothyroidism
– Mental retardation, constipation, failure to thrive
– Treat with thyroxine supplementation

Congenital adrenal hyperplasia
– 21-hydroxylase deficiency
– Salt wasting in males
• Severe hyperkalemia
– Virilization in females
– Treat with corticosteroids and mineralocorticoids
Disorders, cont.

Hemoglobinopathies
– Detect sickle cell disease and variants
– Penicillin prophylaxis

Cystic Fibrosis
– Assurance of proper nutrition and medications

Congenital Deafness
– Not done from the blood spot, of course
– Treat with early intervention strategies to improve
communication skills

SCID
– Analysis for T-cell receptor excision circles (TRECs)
– Reported higher incidence in Navajo population
The Expanding Expanded Screen

Lysosomal storage disorders
– Enzyme replacement therapy
– HB201 (2010)
HB201


Passed in the NM Legislature
New disorders will eventually be added to the NM
newborn screen
–
–
–
–
–


Pompe disease
Krabbe disease
Gaucher disease
Niemann-Pick disease
Fabry disease
The reason for adding to the screen is the availability of
enzyme replacement therapy or bone marrow
transplantation
NM will likely have to wait for Oregon to add these same
tests
Gaucher disease


Lysosomal storage disorder due to defective function of
glucocerebrosidase
Different presentation ages
– Severe infantile form with neurodegeneration
– Intermediate childhood form with some neurologic symptoms
– Very common adolescent and adult form
• Splenomegaly
• Thrombocytopenia
• Bone crises

Treated very effectively for over a decade with enzyme
replacement therapy
– Cerezyme
– Velaglucerase
Fabry disease

Lysosomal storage disorder due to defective
function of alpha-galactosidase A
 Characterized by accumulation of
globotriaosylceramides
– Occurs in the endothelial cells
– Causes blood vessel involvement
– Strokes, renal disease, cardiac disease, peripheral
neuropathy

Effective treatment with ERT
– Fabrazyme
Pompe disease

Pompe disease
– Glycogen storage disease type II
– Lysosomal acid maltase deficiency
– Infantile form
• Severe cardiomyopathy
– Childhood and adult forms
• Skeletal myopathy

Highly effective treatment with enzyme replacement
therapy
– Lumizyme
Niemann-Pick disease

Types A and B due to defective function of
sphingomyelinase
 Types C and D due to defective cholesterol
trafficking
 The newborn screen will be for types A and B by
detecting abnormal sphingomyelinase activity
– Types C and D may be picked up due to somewhat
reduced activity

ERT treatment is still in the research phase but an
is coming
– BMT has been effective in some cases
Krabbe disease





Also known as globoid cell leukodystrophy
Defective activity of lysosomal galactocerebrosidase
Degenerative neurologic disorder with a leukodystrophy
Buffalo Bill quarterback Jim Kelley had a child with the
disorder
Early diagnosis enables bone marrow transplantation
What About Others?

Effective ERT and BMT exists for the
mucopolysaccharidoses
• MPS1
– Hurler, Hurler-Scheie and Scheie
– Aldurazyme
• MPS2
– Hunter syndrome
– Elaprase
• MPS VI
– Maroteaux-Lamy
– Naglazyme

Assay for enzymes in blood spots problematic
What About Others?

Spinal muscular atrophy
– Fairly common deletion of exons 7 and 8 in SMA1

Fragile X syndrome
– Definite research showing that detection of the
trinucleotide repeat is feasible from the blood spot

Other DNA based testing
Resources

Resources
– NM Newborn Screening
• http://www.nmhealth.org/about/phd/fhb/cms/nbgs/
– Oregon Newborn Screening
• http://public.health.oregon.gov/LaboratoryServices/NewbornS
creening/Pages/index.aspx
– March of Dimes
• http://www.marchofdimes.com/professionals/14332_1200.asp
– Save Babies
• http://www.savebabies.org/
– Newborn Screening ACT Sheets
• http://www.ncbi.nlm.nih.gov/books/NBK55827/