Autosomal recessive ataxia with oculomotor apraxia (OMA), elevated levels of serum alpha-fetoprotein (AFP biomarker) and distinct mutations of genes implicated in DNA repair and/or transcription, define a group of early onset disorders including: ataxia-telangiectasia (ATM gene), ataxia-telangiectasia like disorder (MERR11 gene) ataxia with oculomotor apraxia type 1 (AOA1, APTX gene) and type 2 (AOA2, SETX gene; Caldecott, 2003). Here, ATM is linked to ataxia telangiectasia.