Section 15 — Human Genetics 



15.12. (D). Consanguinity Studies in Italy. A. Moroni 

 (Parma, Italy). 



An analysis of consanguineous marriages 

 which have taken place in Italy from 1910 to the 

 present has been started, using consanguineity 

 dispensations available in bishopric archives and 

 at the Vatican. 



About 500,000 dispensations have been 

 examined and are being transferred to magnetic 

 tape for (a) statistical analysis with a view to 

 detect what can be learnt on population struc- 

 ture from the study of the frequency of consan- 

 guineous marriages, (b) linkage, with other types 

 of investigations on records (e.g. hospital, 

 school records, etc.) in order to estimate the 

 effect of inbreeding on mortality disease, 

 anthropometric characters, etc. 



15.13. Recent Investigations about the Direct 

 Estimation of the Mutation-Rate of Autosomal 

 Dominant Genes in Men. Wilhelm Tunte 

 (Miinster, Germany). 



The problem of the frequency of spontaneous 

 mutations in men is an important field of 

 research at the Institute of Human Genetics 

 in Miinster. The starting point for these investi- 

 gations is the Genetic Register for the adminis- 

 trative area of Miinster having been established 

 in 1957. On the basis of experience hitherto ex- 

 isting, it will be discussed to what extent special 

 hereditary diseases are suitable for estimating 

 the mutation-rate. In this connection investi- 

 gations are reported that are now in operation 

 or have been closed in the institute mentioned 

 above. Preliminary findings will be discussed for 

 syn- and polydactylie. Complete results will be 

 brought about multiple cartilaginous exostosis 

 and Osier's disease. 



these conditions were fulfilled with only 183 

 women and 748 men. The material could be 

 expanded by cases which had been collected by 

 E. Kruyff in an investigation on the induction of 

 leukaemia following radiotherapy of ankylosing 

 spondylites. In addition, progeny was scored 

 from a group of males having received low 

 gonad doses of 1-10 rads. Data on the sex ratio, 

 expressed as the percentage of males in the 

 progeny, were extracted from birth records in 

 the municipal registration offices. Following 

 maternal irradiation with 70-270 rads the sex- 

 ratio decreased from 0.541 (242 births) before 

 irradiation to 0.485 (230 births) after irradiation. 

 The shift is not significant, but the data show no 

 heterogeneity with those obtained by Turpin, 

 Lejeune and Rethore (1957) in France. For the 

 combined sets of data the decrease of the sex- 

 ratio after exposure to radiation of women is 

 significant (P= 0.023). Since any of the well- 

 known factors influencing sex-ratio, such as 

 birth order, paternal age and annual fluctuations, 

 including war, cannot account for the observed 

 decrease in sex ratio, we feel justified in con- 

 cluding that it was brought about by radiation-in- 

 duced genetic changes. Non-disjunction would 

 have resulted in an increase of the sex ratio. The 

 consistent decrease in this and similar studies 

 suggests then that the frequency of non-dis- 

 junction in irradiated women, is negligibly small 

 relative to the frequency with which recessive 

 lethals or loss of the X-chromosome are in- 

 duced. Following paternal irradiation (25-370 

 rads) the sex-ratio increased significantly (P — 

 0.035) fiom 0.470 (1258 births) before irradiation 

 to 0.525 (932 births) after irradiation. Here, how- 

 ever, the sex-ratio before irradiation was ab- 

 normally low and differed significantly from the 

 population average, thus no definite conclusions 

 can be drawn. In contrast to results of Lejeune, 

 Turpin and Rethore (1960), no change in the 

 sex-ratio was observed after paternal exposure 

 to doses of 1-10 rads. 



15.14. Sex Ratio Shifts among Progeny from Patients 

 having received Therapeutic X-Irradiation. 

 P. J. L. Scholte and F. H. Sobels (Leyden, 

 The Netherlands). 



The material was collected from four hospitals, 

 situated in The Hague, Leyden and Rotterdam. 

 Selection was made for patients who, following 

 exposure to gonad doses of a few hundred rads, 

 had progeny and who at the time of irradiation 

 did not age more than 36 years for women and 

 41 years for men. Out of a total of 85,000 patients 



Subsidized by the Organisation For Health 

 Research T.N.O. 



15.15. Investigations on the Low Sex Ratio in a 

 Human Population. I. Lester Firschein and 

 Diane Sank (New York, U.S.A.). 



A further statistical analysis of the sex ratio 

 within families will be made in a population 

 known as the "Black Caribs" of British Hon- 

 duras, Central America. Previously it was shown 



274 



