Coffin-Siris syndrome: review and presentation of new cases from a questionnaire study

To clarify the phenotypic variability of Coffin-Siris syndrome, we present a review of the literature and 18 new cases. We performed a questionnaire study of patients ascertained through an international support group. Information on their sibs was available for comparison. The most frequent findings include some degree of mental retardation or developmental delay, "coarse" facial appearance, feeding difficulties, frequent infections, and hypoplastic to absent fifth fingernails and fifth distal phalanges. We discuss the key manifestations for diagnosis, medical and developmental implications, and possible pathogenesis.