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).

• Classic Ataxia Telangiectasia
  • Infancy/childhood
  • ↑ AFP levels 100–900 μg/l. Rarely in <1% normal values are seen^[1]
  • 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^[2].
  • 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

CSF AFP levels in normal infants also decline with gestational age in proportion to levels of AFP in serum^[3][4].

• 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