The frequency of a hereditary abnormality of erythocytes characterised by a deficiency in glucose 6 phosphate dehydrogenase and glutathione instability, has been investigated in various population groups in Israel. The highest frequencies of this abnormality have been detected among Jews from Kurdistan, Iraq and Persia. It is also relatively common in other oriental (sefardic) Jewish communities, as well as among Arabs, desert Bedouins and Druses.
Up to now only one case of this erythrocyte defect has been found among Jews of Ashkenazic origin. The same abnormality has also been found in a Sikh from Punjab.
The hereditary pattern of transmission and evidences of sex linkage are presented. The problem of expressivity of the abnormal gene in heterozygous females is discussed.