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

1. a Verhagen MMM, Abdo WF, Willemsen MAAP, Hogervorst FBL, Smeets DFCM, Hiel JAP, Brunt ER, van Rijn MA, Majoor Krakauer D, Oldenburg RA, Broeks A, Last JI, van't Veer LJ, Tijssen MAJ, Dubois AMI, Kremer HPH, Weemaes CMR, Taylor AMR, van Deuren M. Clinical spectrum of ataxia-telangiectasia in adulthood. Neurology. 2009 Aug 11;73(6):430-7. doi: 10.1212/WNL.0b013e3181af33bd. Epub 2009 Jun 17.
[PMID: 19535770] [DOI: 10.1212/WNL.0b013e3181af33bd]
2. a Schieving JH, de Vries M, van Vugt JMG, Weemaes C, van Deuren M, Nicolai J, Wevers RA, Willemsen MA. Alpha-fetoprotein, a fascinating protein and biomarker in neurology. Eur J Paediatr Neurol. 2014 May;18(3):243-8. doi: 10.1016/j.ejpn.2013.09.003. Epub 2013 Sep 29.
[PMID: 24120489] [DOI: 10.1016/j.ejpn.2013.09.003]
3. a Christiansen M, Høgdall CK, Høgdall EV. Alpha-fetoprotein in human fetal cerebrospinal fluid. Clin Chim Acta. 2000 Jan 20;291(1):35-41. doi: 10.1016/s0009-8981(99)00195-3.
[PMID: 10612715] [DOI: 10.1016/s0009-8981(99)00195-3]
4. a Coakley J, Kellie SJ, Nath C, Munas A, Cooke-Yarborough C. Interpretation of alpha-fetoprotein concentrations in cerebrospinal fluid of infants. Ann Clin Biochem. 2005 Jan;42(Pt 1):24-9. doi: 10.1258/0004563053026763.
[PMID: 15802029] [DOI: 10.1258/0004563053026763]
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