Early-Onset Myopia and Retinal Detachment without Typical Microcoria or Severe Proteinuria due to a Novel LAMB2 Variant

Purpose: To describe the ocular and renal features, as well as outcomes of retinal detachment repair, in patients with a novel, homozygous laminin 0-2 (LAMB2) pathogenic variant. Design: Single -center retrospective chart review of patients with a homozygous variant, c.619T>C p.(Ser207Pro), in the LAMB2 gene. Subjects: Eleven patients (22 eyes) from 4 families. Methods: Demographic data and ocular findings were recorded. Patients were recalled for a detailed renal evaluation. Main Outcome Measures: Ocular features, renal features, and outcomes of retinal detachment repair. Results: The mean age at presentation was 6.0 (range, 1-26) years. None of the study eyes had microcoria, and none of the patients had nephrotic-range proteinuria. The mean refraction and axial length were -7.9 diopters (range, -4.0 to -12.0 diopters) and 25.3 (range, 22.7-27.7) mm, respectively. Eleven eyes (50%) had cataract at presentation. Fifteen eyes had a clear view to the fundus and all showed tessellated myopic fundus, avascular peripheral retina evident clinically or on fluorescein angiography, and rudimentary fovea. Optic disc pallor was observed in 10 eyes (66.7%). Straightened retinal vessels, abnormal vascular emanation (situs inversus) from the optic disc, supernumerary vascular branching at the optic disc, and vascular tortuosity were observed in 10 (66.7%), 2 (13.4%), 2 (13.4%), and 2 (13.4%) eyes, respectively. Discrete areas of punched -out chorioretinal atrophy were observed in 4 (26.7%) eyes. Spectral -domain OCT showed retinal and choroidal thinning in 13 eyes (86.7%), retinoschisis temporal to the fovea in 2 eyes (13.4%), and rudimentary fovea in 15 eyes (100%). Among the 22 eyes, 14 eyes (63.6%) developed rhegmatogenous retinal detachment (RRD), mostly during childhood, of which 5 patients had bilateral RRD. Eight eyes were operated on and 6 (75%) achieved retinal reattachment at the last follow-up. The mean preoperative visual acuity was 20/300 and the mean postoperative visual acuity at the last follow-up was 20/400. Conclusions: This study describes a distinct phenotype of LAMB2-related disease with a novel, homozygous LAMB2 variant, and further expands the spectrum of ophthalmic and renal features, and the molecular genetic basis, of LAMB2-related disease. Because the typical microcoria and nephrotic-range proteinuria might be absent, the retinal features can guide the diagnosis.