Abstract
Abstract: :
Purpose: To identify the responsible mutation in a patient with retinitis punctata albescens and to evaluate the fundus appearance and retinal function in the patient and his asymptomatic parents. Methods: The 9 exons of the RLBP1 gene were individually amplified from leukocyte DNA of the proband. The amplified DNA fragments were screened for mutations by either single-strand conformation analysis (SSCP) and/or direct genomic sequencing. Both the patient and his parents had a comprehensive ophthalmic examination. The parents and the proband each had a full-field electroretinographic recording and one parent had static perimetry testing with a Tübinger perimeter. Results: The proband was a compound heterozygote with two novel mutations in the RLBP1 gene. One mutation was a frameshift, Gly31(2-bp del)(GGA≷G--), and the other was a missense change, Arg151Trp (CGG≷TGG). Each parent carried one of the these two mutations. The 7-year-old proband showed numerous white spots throughout the fundus and severe functional impairment of his rod photoreceptor cells (isolated rod ampltiude, non-detectable; cone amplitude, normal). ERG rod and cone amplitudes and psychophysical rod thresholds were normal in the parents, after a standard 30 to 40 minutes of dark adapatation. However, the fundi of both parents had white spots reminiscent of those seen in the proband, although considerably less in number. Conclusion: Although heterozygotes with recessive RLBP1 mutations may not demonstrate functional impairment of the retina, they can have white spots within the retina or retinal pigment epithelium as a sign of their carrier status.
Keywords: 562 retinal degenerations: hereditary • 420 genetics • 395 electroretinography: clinical