黒毛和種子牛に発生した遺伝性内水頭症の染色体領域の解明

Abstract

Congenital internal hydrocephalus (CIHY), characterized by cranial doming, paresis and ataxia at birth, has been occurring in Japanese Black calves in Tohoku area since 1988. The sires of the affected calves were of the same pedigrees. Embryo transfer was used to investigate the causative genes by producing several calves from a cow that delivered a calf with CIHY. The cow was superovulated by FSH and inseminated with the frozen semen of the suspected bull. Ultimately, ten calves were birthed from the recipient cows, with five showing symptoms of hydrocephalus. Clinically, four of the affected calves showed paresis, cranial doming and strabissumus. One calf showed a chronic convulsion and ataxia at 29 days and died. The pathological finding noted bilateral enlarged ventricles with an increase in cerebrospinal fluid. Gene scanning was performed with microsatelite markers using tissues and blood from five of the affected calves and five full-sib calves and the splenic tissues of eighteen half-sib calves that were embedded in paraffine for pathological study. The suspected gene was found near the centromere of chromosome 3 (BTA3). Using DNA markers, the common region of CIHY was found to be between MB101 and DIK069. The pidemiological findings clarified this CIHY as a single autosomal recessive disease.