Objectives To identify novel complement factor H (CFH) gene mutations and to specify the clinical characteristics in patients with basal laminar drusen (BLD), a clinical subtype of age-related macular degeneration.
Methods Twenty-one probands with BLD were included in this study. The ophthalmic examination included nonstereoscopic 30° color fundus photography, fluorescein angiography, and high-resolution spectral-domain optical coherence tomography. Renal function was tested by measurement of serum creatinine and urea nitrogen levels. Venous blood samples were drawn for genomic DNA, and all coding exons and splice junctions of the CFH gene were analyzed by direct sequencing.
Results In 3 families, we identified novel heterozygous mutations in the CFH gene: p.Ile184fsX, p.Lys204fsX, and c.1697-17_-8del. Ten of 13 mutation carriers displayed the BLD phenotype with a wide variety in clinical presentation, ranging from limited macular drusen to extensive drusen in the posterior pole as well as the peripheral retina. Two patients with BLD developed end-stage kidney disease as a result of membranoproliferative glomerulonephritis type II.
Conclusions The early-onset BLD phenotype can be caused by heterozygous mutations in the CFH gene. Because some patients with BLD are at risk to develop membranoproliferative glomerulonephritis type II, we recommend that patients with extensive BLD undergo screening for renal dysfunction.
Clinical Relevance Elucidation of the clinical BLD phenotype will facilitate identification of individuals predisposed to developing disease-related comorbidity, such as membranoproliferative glomerulonephritis type II. Moreover, with upcoming treatment modalities targeting specific components of the complement system, early identification of patients with BLD and detection of the genetic defect become increasingly important.