PROBABLE LINKAGE BETWEEN A CONGENITAL CATARACT LOCUS AND THE DUFFY BLOOD GROUP LOCUS.

Abstract

SUMMARYThe large family of Nettleship (1909), which manifests one type of congenital cataract, has been studied in a search for linkage. Clinical details are given. By computer analysis, linkage of the relevant gene locus with the ABO, MNS, Rhesus, P, Kell or Secretor loci is rendered unlikely. However, there is a strong indication of close linkage with the Duffy locus; the final probability of linkage, after combination with an a priori probability against linkage, is assessed as 0–977. The extensive data of Mohr (1954), on a different type of cataract (Marner, 1949), are also fully analysed for linkage relationships, but no firm indication of linkage is found with the ABO, MNS, Rhesus, P, Lutheran or Secretor loci. For this type, the final probability of linkage with the Duffy locus is assessed as only 0–02 and it is believed that a different cataract locus is concerned.Both authors are grateful to Prof. L. S. Penrose for his help and encouragement. We are indebted to Dr A. E. Mourant for most of the anti‐sera used, to Dr D. Lehane and Prof. P. L. Mollison for anti‐Fyα; serum and to Dr B. Chown for anti‐Fy6. Thanks are due to Miss R. Marshall and Miss M. M. Izatt for their help in the blood grouping studies and to Mrs J. Schulze who, with the assistance of Mrs N. Ruth and Mrs D. Martin, organized the linkage calculations most efficiently, using facilities made available by Dr V. A. McKusick, largely from grant RG‐6642 of the National Institutes of Health. Both authors wish to acknowledge the financial support of the Medical Research Council. A Hamblin slit‐lamp was purchased with a grant from the special equipment fund of the University of London. Appendix III has been kindly contributed by Dr C. A. B. Smith.