Nine family cases of diabetes are genetically interpreted on account of a polygenic model of inheritance, with each allele being characterized by a different probability of chronological stability of the normal information. This model provides a satisfactory interpretation of the clinical and subclinical variability of diabetes — which the diallelic model is unable to do — and has on the polygenic model the advantage of a higher fitness to a case of discontinuous variability, such as diabetes. Both pedigrees characterized by apparent recessive inheritance and those characterized by apparent dominant one may equally be interpreted on account of the polyallelic model.

The origin of polyallelism is attributed to the hereditary variability of the gene's temporal unit (chronon). As a result, the phenomenon of “anticipation” may also be interpreted, and the one-origin clinical and sub-clinical variability of diabetes be demonstrated.

The frequency of twins and triplets was significantly higher than expected among 56 patients with Klinefelter's syndrome (7.1%), compared with 1.58% in the population (P<0.001), and the frequency of multiple births in the 56 sibships (4.08%) was also significantly higher than expected (P<0.01).

One of 15 patients with the XYY syndrome was a twin, and there were 2 twin births among the 53 births in the 15 sibships.

A review of 15 chromosomally abnormal twin pairs indicates that finger and hallucal patterns of the affected twin are more similar to other patients than to the normal cotwin.

Correlation coefficients of TFRC and atd angle differences tend to remain similar in spite of the presence of chromosome abnormality in the cotwin. This supports the use of dermatoglyphic analysis as a means for diagnosing twin zygosity. Correlation coefficients of intrapair TFRC and atd angle differences in 25 control MZ twin pairs shows good agreement in zygosity determinations, when compared to results obtained by blood group and clinical observation studies.

In a series of 155 female and 142 male MZ twin pairs, TFRC and atd angle differences plotted on a graph against the frequency of occurrence illustrate that the range of variation is greater among females. Further study of a large series of twin pairs, however, is necessary to determine whether this is an effect of lyonization or the alteration of the polygenic complex of dermal configuration by the X chromosome.

The palm prints of a 2A,XY/3A,XXY patient displayed a scarcity of patterns and a wider than normal atd angle. Both hands had typical four-finger lines. The digits of the right hand had radial loops on II, III and V.

This note describes the dermatoglyphic disturbances verified in two patients with a very complex and highly mutilating syndrome. The parents of the affected individuals present, however, normal dermatoglyphics.

The authors present the case of a 42 years old hermaphrodite, showing bilateral ambigonadism with female nuclear sex and 46,XX karyotype. The psychological analysis reveals a female personality, which is in contrast with the male civil status: hence, a source of frustration and social inadaptation.

The case of a 13-year-old boy with Mediterranean disease, hypogammaglobulinemia and XYY sex-chromosome constitution is presented. The somatic cells contained 47 chromosomes. No chromosomal abnormalities were found in the parents and in the brother. The findings are discussed in relation to the previously reported cases of XYY males.

In a girl affected by mental deficiency and slight malformations, a 46,XX, 18r chromosome set was found. Metaphases with irregularly sized or absent rings amounted to 14% in peripheral blood cultures. Tritiated thymidine incorporation pattern in the ring chromosome was similar to that of the normal 18 chromosome.

A new hypothesis involving two genes has been proposed to explain the nature of hairy pinnae of the ear. The insignificant values of the goodness of fit χ2 seem to confirm the proposed hypothesis.

An unusual ear type in man involving a folding of the helix is described in a pedigree with three generations. The trait seems to be due to an autosomal dominant gene with variable expressivity.

Twinning rates in Nigeria are much higher than in Europe and USA, and appear to be highest in its western and eastern parts. The twinning incidence in a representative population in a town in Western Nigeria, Igbo-Ora, is approximately four times that in Europe and USA.

Zygosity determination has shown that only 8.6% of newborn twin pairs in Ibadan are MZ, compared to approximately 30% in Caucasian populations. Studies in Igbo-Ora have also given similar results, confirming the view that high twinning incidence in Nigeria is due to a very high DZ twinning rate, the MZ rate being the same as in Europe and USA.

The proportion of twins with monochorionic placentae in Ibadan is about 5%, against approximately 20% in UK and USA. The twinning rates in the two populations are 45‰ and 11‰ respectively. This inverse relation (between the twinning rate and the proportion of monochorionic placentae) may be used in calculating the twinning incidence in a population in which the proportion of twins with monochorionic placentation is known.

The high rate of twinning in rural areas is suggested to be due to higher coefficient of inbreeding, better physical conditions of mothers on the countryside and higher mean birth order. Family data indicate the frequent role of maternal genotype in DZ twinning.

Skin reflectances were obtained at 685 mμ wave length from the medial upper arm and the forehead regions among 105 Tibetan males and 105 Tibetan females, in order to study sex differences in human skin pigmentation. The forehead pigmentation of males was always found to be darker than that of females, and the difference to be significant during middle and late adolescence The medial upper arm pigmentation of girls was found to be darker than that of boys, during early adolescence; but during middle adolescence the two sexes exhibited just similar pigmentation and during late adolescence females emerged to be significantly lighter than males. The present study, thus, suggests that one of the factors causing sex differences in human skin pigmentation may be the physiological changes occurring during adolescence, which may be genetically determined.

Five families with cases of erythroblastosis foetalis have been studied for the ABO, Rh, MN, and Kell-Cellano blood group systems. In all of them, the father and mother were found to be compatibly mated, and so were the children with their mother, in all systems, except Rh.

Most children were of CDe/cde type, and all mothers cde/cde. The influence of other systems (MN and Kell-Cellano) on Rh incompatibility remains to be investigated. They might play a role in counteracting the effect of Rh incompatibility.

The antibody titre in the mother's blood has clearly appeared to decline gradually, with an increasing time gap between successive pregnancies.

Whether the possibility of having a normal full term pregnancy, resulting in the birth of a healthy child, increases, if the time gap between two successive pregnancies is larger, remains to be investigated.

With the revision of application of terms “endogamous” and “exogamous” the inbreeding levels have been calculated from certain parts of Madhya Pradesh. Higher inbreeding levels in persons with rural background are in conformity with other workers.