Although these mutations localize outside of repeats 2 and 3, involved in binding MDC1 and RNF8, such WRAP53β mutants are excluded from the nucleus where MDC1 and RNF8 exert their function, indicating that interaction between these proteins likely is impaired in WRAP53β-associated dyskeratosis congenita. The gene discussed is MDC1; the disease is dyskeratosis congenita.