1' Cytogenetic

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Types of Genetic Tests

• 1. Cytogenetic
• 2. DNA
• 3. Metabolic

Biochemical
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• What is Phenylketonuria?
• Rare, metabolic disorder--inability to
  metabolize the amino acid phenylalanine
• usually due to mutations in the gene encoding
  the liver enzyme phenylalanine hydroxylase
• Consequences if excess phenylalanine
  accumulates in blood and tissue--irreversible
  brain damage and mental retardation
• autosomal recessive
• affects 1/10,000 -1/20,000 births in Caucasian
  and Asian populations

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• The good news
• With early, careful and continued treatment,
  the levels of phenylalanine in the blood can be
  controlled
• Normal 1 mg/dl
• PKU (with treatment) 2-10 mg/dl
• PKU (out of control) gt30 mg/dl
• Treatmentdiet with some phenylalanine (its
  essential for normal growth) but much lower than
  usual
• - avoid high protein foods (meat, eggs, milk
  etc)
• - measured amounts of cereals, fruits and
  vegies
• - phenylalanine-free formula for babies
• Treatment must be life-long

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History of Newborn Screening in North Carolina

• 1965 - Phenylketonuria
• 1979 - Hypothyroidism
• 1987 - Sickle cell disease (limited)
• 1988 - Galactosemia
• 1989 - Congenital adrenal hyperplasia
• 1994 - Sickle cell disease (universal)
• 1997 - Tandem mass spectrometry (MS/MS)
• Amino acid disorders
• Organic acid disorders
• Fatty acid disorders

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homework for Thursdays guest lecture.. Dr. Shu
Chaing, Director North Carolina Newborn Screening
Program

• read about the types of conditions screened for
  in NC
• http//slph.state.nc.us/Newborn/ConditionsTested.a
  sp
• look up info on your own about these disorders
• 1. Amino acid Maple syrup urine disease
  (MSUD)
• 2. Organic acid 3-Hydroxy-3-methylglutaryl-CoA
  
• lyase deficiency (HMG)
• 3. Fatty acid Medium-chain acyl-CoA
• dehydrogenase deficiency (MCAD or MCADD)