Pigmented Paravenous Chorioretinal Atrophy

A number sign (#) is used with this entry because of evidence that pigmented paravenous chorioretinal atrophy (PPCRA) is caused by heterozygous mutation in the CRB1 gene (604210) on chromosome 1q31.

Description

Pigmented paravenous chorioretinal atrophy is a stationary disease of the ocular fundus in which bone corpuscle pigmentation is seen in a paravenous distribution. Patients are usually asymptomatic; diagnosis is based on the characteristic fundus appearance. Most cases have been reported in males (summary by Traboulsi and Maumenee, 1986).

Clinical Features

Skalka (1979) reported affected father and son. Traboulsi and Maumenee (1986) described a family in which the condition occurred in a mother and her 3 sons and was associated with hyperopia, esotropia, and vitreoretinal degeneration. The findings were milder in the mother and severe in the 3 children; strabismus and hyperopia occurred only in the sons.

Noble (1989) reported 3 brothers, born of nonconsanguineous parents, who showed characteristic paravenous bone spicule accumulation. The onset in all 3 brothers was early in life (possibly congenital) and there was minimal, if any, progression. The brothers were aged 37, 41, and 56 years. The parents were reportedly normal but were not examined. Noble and Carr (1983) described 6 patients, of whom 3 were female.

McKay et al. (2005) reported a family in which 6 members had pigmented paravenous chorioretinal atrophy. The earliest clinical sign in this family was subtle symmetrical chorioretinal atrophy in the inferior quadrant. Paravenous pigmentation occurred initially in the far periphery, progressing centrally, with atrophy later becoming more widespread, involving the nasal, then the temporal, and finally the upper quadrant. PPCRA was dominantly inherited in this family but exhibited variable expressivity. McKay et al. (2005) noted that males were more likely to exhibit a severe phenotype, whereas females might remain virtually asymptomatic, even in later years.

Choi et al. (2006) followed 15 patients (8 males and 7 females) with PPRCA for 3 to 35 years (average 13 years) and quantified the mean annual changes in visual acuity, visual field area, and full-field electroretinogram amplitude. The results indicated that loss of peripheral vision in PPRCA is slowly progressive.

Inheritance

Father-to-son transmission of PPCRA in the family reported by Skalka (1979) indicated autosomal dominant inheritance. The pedigree described by Traboulsi and Maumenee (1986) was considered consistent with X-linked inheritance because the sons were more severely affected than the mother.

PPCRA was dominantly inherited in the family reported by McKay et al. (2005).

Molecular Genetics

In all 6 affected members of a family segregating PPCRA, McKay et al. (2005) identified heterozygosity for a val162-to-met (V162M; 604210.0010) mutation within the fourth EGF-like domain of the CRB1 gene.