Data for X‐mapping calculations, Israeli families tested for Xg, g‐6‐pd and for colour vision

The results are recorded of tests for the X‐linked red cell antigen Xg^a on families with glucose‐6‐phosphate dehydrogenase deficient members. The families live in Israel and belong to Kurdish, Iraqi, Yemenite, Sefardic and Ashkenazy Communities. Linkage between Xg and g‐6‐pd is established at the 1 in 100 level of probability, and an estimate of the recombination frequency is 0–273 + 0–072. Some of the families also have colour vision abnormalities but the information is not enough to allow an estimate of the recombination fraction between Xg and c.v. to be made. However, the results strongly suggest that the locus for c.v. is further away from Xg than is g‐6‐pd: consequently the probable order on the X chromosome of these three loci is Xg … g‐6‐pd … c.v. We wish to express our gratitude to all the doctors who collaborated with us by providing some of their material. Special thanks are due to Mrs Judith Offer (Hakfar Hayarok), Dr Rina Schmidt and Dr G. Kende (Government Hospital, Tel‐Hashomer, Israel) for their great part in collecting the samples of blood; and to Prof. E. Auerbach and Dr Edith Nelken, of the Vision Research Laboratory, Hadassah Medical School, Jerusalem, who made detailed colour vision tests in one of our families. We are greatly indebted to Dr J. D. Mann of the Butterworth Hospital, Grand Rapids, and to Dr Amos Cahan of Knickerbocker Biologicals, New York, for generous supplies of the most precious anti‐Xg^a plasma. The work has been supported in part by Grant A‐2740‐Hema. from the U.S. Public Health Service, and R/00014 from the World Health Organization.