IgA deficiency in one of identical twins.

A disease resembling childhood coeliac disease occurred in one of identical twins. When the twins were investigated at the age of 23 the initial diagnosis could not be substantiated but the twin who had been ill had selective IgA deficiency. Differences dating from early infancy may have been a result of the discordance for IgA deficiency. Thus in some patients environmental influences may be important in either the initiation or the perpetuation of the deficiency.