Kato T, Kato Y, Matsumoto H, et al. - Mutation in the aprataxin (APTX)-coding gene APTX, which is involved in DNA single-strand break repair (SSBR), is suggested as causative for early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH), which is a neurodegenerative disorder.

Although there are similarities between the neurological abnormalities associated with EAOH and those observed in patients with ataxia-telangiectasia, uncertainty remains concerning the immunological abnormalities in patients with EAOH. As per this study, EAOH patients show immunological abnormalities, including lymphopenia; reduced levels of CD4+ T-cells, CD8+ T-cells, and B-cells; hypogammaglobulinemia; low T-cell recombination excision circles and kappa-deleting element recombination circles; and oligoclonality of T-cell receptor β-chain variable repertoire. The EAOH patients varied in these immunological abnormalities. In addition, the lymphocytes obtained from the patients with EAOH showed mild radiosensitivity. Per these findings, the immunological abnormalities and mild radiosensitivity observed in patients with EAOH could be due to the DNA repair defects.