Medical Genetics In certain illnesses, intrauterine events may be implicated (eg, maternal alcoholism in some cases of DiGeorge anomaly; in others, drug ingestion may be implicated(eg, phenytoin in iga deficiency). The exact biologic abnormality in most of the illnesses is unknownMedical Genetics In certain illnesses, intrauterine events may be implicated (eg, maternal alcoholism in some cases of DiGeorge anomaly); in others, drug ingestion may be implicated (eg, phenytoin in IgA deficiency). The exact biologic abnormality in most of the illnesses is unknown