North Carolina Macular Dystrophy: Long-term Follow-up of the Original Family

Abstract

Purpose: The phenotype of North Carolina macular dystrophy (NCMD) is highly variable and remains poorly appreciated and understood, often causing misdiagnoses in isolated cases. One of the features of NCMD is the general lack of progression despite its original name, "dominant progressive foveal dystrophy," as reported in 1971 by Lefler et al (W.H.L.). The purpose of this study was to report the long-term follow-up of this condition.

Design: Systematic, longitudinal, and detailed documentation along with the imaging of the peripheral retina.

Subjects: We reexamined 27 of the original family members with NCMD in an office setting 30 to 50 years after they were first reported.

Methods: The evaluation of all the affected subjects included best-corrected visual acuity (BCVA), slit-lamp and dilated-fundus examinations, wide-field fundus and autofluorescent photography, and spectral-domain OCT (SD OCT). Blood was collected for DNA extraction, banking, and sequencing.

Main outcome measures: Best-corrected visual acuity, slit-lamp and dilated-fundus examinations, wide-field fundus and autofluorescent photography, and SD OCT.

Results: The 27 subjects examined were a part of the original family with NCMD that was initially reported in 1971. A point mutation (NC_000006.11:g.100040906G>T) (Hg19) in a noncoding region of a deoxyribonuclease I hypersensitivity binding site was found in all the affected subjects. Nine subjects were the affected children of those originally examined 30 to 50 years ago by Kent W. Small (K.W.S.) and W.H.L., and the remaining 17 subjects (34 eyes) had been examined 30 years previously by K.W.S. Of these 17 subjects (34 eyes), 4 of 34 (11%) eyes showed worsening of vision and evidence of fibrosis due to choroidal neovascular membranes (CNVMs). Fourteen of the 27 (51%) patients showed peripheral retinal drusen, which did not seem to correlate with the severity of the macular disease.

Conclusions: Most patients with NCMD have stable vision and fundus findings throughout their lives. The ones who experienced BCVA decline did so because of the apparent evidence of CNVMs. Patients with grade 2 NCMD seem to be at an increased risk of further or progressive vision loss due to CNVMs. Intravitreal therapy with vascular endothelial growth factor inhibitors may benefit these patients if they are treated in a timely fashion. Peripheral retina drusen of varying degrees of severity were found in slightly more than half of the affected subjects.

Keywords: Choroidal neovascular membranes; DNase I hypersensitivity binding site; North Carolina macular dystrophy; PRDM13; Peripheral drusen.