In this week's PNAS Early Edition, investigators at the University of Iowa Carver College of Medicine report their use of exome sequencing "to identify a homozygous Alu insertion in exon 9 of male germ cell-associated kinase as the cause of disease in an isolated individual with RP," or retinitis pigmentosa. The Iowa team screened 1,798 additional, unrelated RP patients and found 20 others who, like the proband, were homozygous for this insertion.