Retinitis Pigmentosa 84
A number sign (#) is used with this entry because of evidence that retinitis pigmentosa-84 (RP84) is caused by homozygous mutation in the DHX38 gene (605584) on chromosome 16q22.
For a general phenotypic description and a discussion of genetic heterogeneity of retinitis pigmentosa, see 268000.
Clinical FeaturesAjmal et al. (2014) reported 4 affected sibs from a consanguineous Pakistani family with early-onset retinitis pigmentosa and macular coloboma. All of the sibs had developed night blindness at 4 years of age, and all were completely blind (no light perception). Funduscopic examination of the proband showed severely attenuated retinal vessels throughout the fundus, and the maculae were severely affected bilaterally, with unusually prominent and deep macular colobomas devoid of neuroretinal tissue. Electrophysiologic responses of both rod and cone photoreceptors were severely reduced compared to control.
Latif et al. (2018) reported 2 consanguineous Pakistani families (MA88 and MA157) segregating early-onset retinitis pigmentosa. Affected members of both families, all of whom were older than age 20 years at the time of report, developed night blindness between ages 3 and 4 years and complete blindness between ages 7 and 8 years. Affected members of family MA88 retained light perception, whereas affected members of family MA157 had no light perception. In family MA88, the 3 affected males were diagnosed with bilateral cataracts at age 6 years; of the 2 affected females, one developed cataracts at age 19 years and the other did not have cataracts at age 20. In family MA157, all 6 affected members (5 males and 1 female) developed cataracts by about age 10 years. Funduscopy in the 3 affected females showed macular atrophy, attenuation of arteries, and clustered area of intraretinal pigment on the periphery. Bilateral cataract in affected males prevented funduscopy findings in the affected males.
InheritanceThe transmission pattern of retinitis pigmentosa in the family reported by Ajmal et al. (2014) was consistent with autosomal recessive inheritance.
Molecular GeneticsIn 4 affected sibs from a consanguineous Pakistani family with early-onset retinitis pigmentosa and macular coloboma, Ajmal et al. (2014) identified homozygosity for a missense mutation in the DHX38 gene (G332D; 605584.0001). The mutation was present in heterozygosity in their unaffected parents and 2 unaffected brothers, but it was not found in 180 ethnically matched controls or in the Exome Variant Server, 1000 Genomes Project, or dbSNP databases.
In affected members of 2 consanguineous Pakistani families (MA88 and MA157) with early-onset retinitis pigmentosa, Latif et al. (2018) identified homozygosity for the same missense mutation in the DHX38 gene (R324Q; 605584.0002). Mutation analysis in 3 members of each family with normal vision tests did not identify the mutation.