Alpha-Feto protein, serum

• any type of movement disorder in early childhood, cerebellar ataxias, oculomotor apraxia(saccadic impairment)

Alpha-fetoprotein (AFP) is present in fetal serum in concentrations up to 5,000,000 μg/l. Postnatally AFP gene expression is turned down with a subsequent fall of the serum concentrations to 'adult values' of about 0.5-15 μg/l from the age of 2 years onwards. Individuals with AFP deficiency and those with hereditary persistence of AFP can however be normal. During pregnancy, AFP (in maternal serum) has long been recognized as a marker for congenital anomalies of the fetus. AFP is also a biomarker for hepatocellular carcinoma and some other malignancies.

Increased serum AFP is a biomarker for Ataxia Telangiectasia, ataxia-oculomotor apraxia 2 (AOA2), Deoxyguanosine Kinase Deficiency(DGUOK) deficiency (hepatocerebral form of mtDNA depletion). Measurement of serum AFP is very useful in the diagnostic workup of autosomal recessive cerebellar ataxias (ARCAs).

CSF AFP levels in normal infants also decline with gestational age in proportion to levels of AFP in serum^[1][2].

• median 61 kIU/L (5th-95th centile: 2-889 kIU/L) in infants -69 to 31 days old
• median 1.2 kIU/L (5th-95th centile: 0.1-12.5 kIU/L) in infants 32 to 110 days old

• Classic Ataxia Telangiectasia
  • Infancy/childhood
  • ↑ AFP levels 100–900 μg/l. Rarely in <1% normal values are seen^[3]
  • in Variant A-T (ATM) AFP levels are 50–500 μg/l
  • other laboratory markers include immunoglobulins, liver transaminases, chromosomal rearrangements, increased radiosensitivity
• Ataxia with Oculomotor Apraxia Type 1 (AOA1)
  • AOA1 (APTX)
    • AFP 10-20 μg/l. ↑ AFP seen only in exceptional cases^[4].
  • AOA2 (SETX)
    • Adolescence/adulthood
    • AFP 10–100 μg/l
    • ↑ Serum Creatine kinase
  • AOA2 (PIK3R5)
    • Adolescence/adulthood
    • AFP 30–100 μg/l
    • ↑ Serum Creatine kinase
  • AOA2 (none-SETX/none-PIK3R5)
    • Adolescence/adulthood
    • ↑ Serum Creatine kinase
• Mitochondrial disorders (POLG and C10orf2)
  • infancy/childhood/adolescence/adulthood
  • raised serum/csf lactate