The lack of influence of parental age and birth order in the aetiology of nuclear sex chromatin‐negative Turner's syndrome

Summary Among seventy patients with nuclear sex chromatin Turner's syndrome sixty‐three individuals were found who had at least one liveborn sib. In these sixty‐three families the observed maternal age (25.413 ± 5.494, S.E. 0.692) did not differ significantly from the expected maternal mean (26.091 ± 5–262); nor did the paternal observed age (27.742 ± 5.651, S.E. 0.718) differ significantly from the expected paternal mean (28.421 ± 5.612). The observed birth ordinal (2.127 ± 1.550, S.E. 0.195) was not significantly different from expected birth ordinal (2.405 ± 1.644). Limitations due to residual fertility of parents are, in this survey, regarded as minimal. It is a pleasure to acknowledge that the beginnings of this survey lay in conversations between Prof. L. S. Penrose and one of us (S. H. B.). We wish to thank Mrs Barbara Latrobe and Mrs Jane Schultz for their assistance.