Linkage and crossing-over in the human sen chromosomes

Summary

Previous knowledge regarding the inheritance of sex-linked congenital stationary night-blindness, myopia, and deuteranopia is discussed, and the necessity of obtaining information concerning the linkage of human characteristics and the crossing-over of human sexchromosomes is indicated.

A pedigree is described in which the transmission of associated night-blindness, myopia, and deuteranopia through seven generations of a family is exhibited. The mode of transmission of the defects shows that they are sex-linked and were originally all located on oneX-chromosome but have, on several occasions, been separated by crossing-over of the maternalX-chromo somes. An estimate of the cross-over ratio between the genes for night-blindness (with myopia) and deuteranopia in human beings is given, enabling the distance between these genes to be determined.

Details are given regarding the affected individuals and the method of compiling the information. A Statistical Appendix by Prof. J. B. S. Haldane, F.R.S., gives a full mathematical treatment of the data.

Finally, the author wishes to express his indebtedness and gratitude to all those members of the family who have co-operated so sincerely in making this work possible, and particularly to Paul I. Wilson (VI. 18) for his invaluable assistance in helping the writer to make contact with the members of the family. The author is much indebted also to the Medical Research Council for a grant which enabled the completion of the work; to Mr Rudd for the invaluable aid described earlier; to Dr J. W. MacArthur of Toronto University for testing sundry members located in Toronto; to numerous ophthalmologists; and to Prof. J. B. S. Haldane, F.R.S., for his help, criticism and encouragement of this work.