Methyprylon-induced bone marrow suppression in siblings. An inherited defect?

Transient bone marrow suppression in two sisters followed ingestion of the sedative-hypnotic drug methyprylon. No other pharmacologic or environmental inciting factor common to both patients was identified. The mechanisms responsible could not be defined; abnormal suppression fo granulocyte progenitors by the drug in vitro was not demonstrable. It is postulated that a pharmacogenetic interaction may have been responsible for methyprylon-related bone marrow suppression in these two siblings.