Piebald Trait With Neurologic Defects

Clinical Features

Telfer et al. (1971) described 2 families in which cerebellar ataxia, impaired motor coordination, and mental retardation of variable severity were associated with piebald traits (see 172800). Some affected persons were deaf. There were some dorsal areas of leukoderma as well as the usual ventral ones. One kindred had 11 affected persons in 3 generations with male-to-male transmission. The separateness from piebald trait without neurologic defects is not clear. Finucane et al. (1991) provided follow-up on 1 of the 2 families. The identification of the fragile X syndrome (300624) provided an explanation for the mental retardation in the proband and no evidence of ataxia was identified; motor incoordination in this patient, then 59 years old, was no more pronounced than that seen in many patients with the fragile X syndrome of similar IQ and age. The second family was not available for study.

Molecular Genetics

Exclusion Studies

In the patient originally described by Telfer et al. (1971) and restudied by Finucane et al. (1991), Fleischman (1992) screened the PCR products from 5 exons of the KIT gene (164920) that encode most of the tyrosine kinase domain, but did not find any nucleotide alterations.