NHP2 and dyskeratosis congenita: In addition to a Dubowitz syndrome diagnosis, the phenotypes of Patients 1 and 2 overlapped with the clinical spectrum of dyskeratosis congenita; an evaluation for this disorder prompted the discovery of markedly shortened telomere length [11] and abnormal colony survival and neutral comet assays, but no mutations in the known dyskeratosis congenita genes TERT, TERC, DKC1, TINF2, WRAP53, NOP10, NHP2, CRC1 or RTEL1. Forty additional telomere biology genes were normal upon careful evaluation of exome sequencing data.