Fig. 2.
Coincidental rare Mendelian diseases: Dulling Occam’s razor. (A) Brother (left) and sister (right) with Brown-Vialetto-van Laere syndrome type 2, distal renal tubular acidosis, hearing loss, and mitochondrial topoisomerase 1 deficiency. (B) The family pedigree; double line indicates consanguinity. There were seven previous spontaneous abortions. Below each patient symbol is a list of that individual’s pertinent gene variants. The table lists the genes and the family’s associated diseases, all recessive disorders. Abbreviations: cmpd het = compound heterozygous; homo = homozygous; SAB = spontaneous abortions. (C) Response of the proband’s cultured fibroblasts to EPI-743 compared with inactive compound (RS-743) in the presence of oxidizing agents. The patient’s fibroblasts have increased sensitivity to oxidizing compounds, and EPI-743 rescues cell viability. (Courtesy of Edison Pharmaceuticals, Inc.) (D) Pedigree of a non-consanguineous family with multiple disorders; asterisks denote allele pairs causing disease.