We excluded mutations in the genes implicated so far in DC and HHS: DKC1, hTERT, hTR, NOP10, NHP2, and TINF2. We performed a detailed investigation of the telomeric phenotype in cells derived from the affected siblings and found no evidence for reduced level or activity of the telomerase catalytic core. The gene discussed is TINF2; the disease is hypotrichosis 1.