ClinVar

In affected members of a large American family of Swiss-German descent with autosomal recessive posterior column ataxia with retinitis pigmentosa (609033) reported by Higgins et al. (1997), Rajadhyaksha et al. (2010) identified a homozygous 361A-G transition in the FLVCR1 gene, resulting in an asn121-to-asp (N121D) substitution at a highly conserved residue in a transmembrane-spanning segment. The family had previously been reported by Higgins et al. (1997). The disorder was characterized by childhood onset of retinitis pigmentosa and proprioceptive loss. The disorder was progressive, with affected individuals becoming blind by the third decade and having severe sensory ataxia and muscle weakness and atrophy.

In a Pennsylvania Mennonite patient with posterior column ataxia and retinitis pigmentosa, Puffenberger et al. (2012) identified homozygosity for the N121D mutation in the FLVCR1 gene. The variant was detected in heterozygosity in 5 of 406 Mennonite control chromosomes, for a population-specific allele frequency of 1.23%. (Puffenberger (2012) stated that the correct population-specific allele frequency data appear in Table 4; corresponding data in the text are incorrect.)