The Authors analyze the phenomenon whereby, in progressing from generation to generation, a hereditary disease may appear at an earlier, equal or later age (anticipation, repetition or posticipation, respectively). They believe that this represents the phenotypic effect of a temporal dimension of the gene, the “chronon”, which may reveal stability, plus-variance or minus-variance according to the standard genetic models. This interpretation provides an explanation of two family cases of diabetes mellitus, respectively exhibiting anticipation and posticipation, and repetition.

Monozygotic twin (MZ), dizygotic twin (DZ), and sibling (SIB) pairs were taste-tested for hydrochloric acid, 1-quinine sulfate, and 6-n-propylthiouracil (PROP). The numbers of pairs involved were 75 MZ, 70 DZ, and 78 SIB, for the latter two compounds; 26, 45, and 45, respectively, for the acid.

There was a significant difference in intrapair variance, between the MZ and the same-sex DZ pairs, in thresholds for bitter-tasting 6-n-propylthiouracil (p < .001). The difference in intrapair threshold variance was not significant for bitter-tasting quinine (p > .05) or for sour-tasting hydrochloric acid (p > .10).

The male MZ pairs had a significantly lower intrapair threshold variance than the male DZ or male SIB pairs for hydrochloric acid (p < .01), but the female pairs manifested no such difference. The intrapair variance in hydrochloric acid threshold was significantly less for the nine male MZ pairs than for the 17 female MZ pairs (p < .02).

Repeated taste tests on the same subjects reproduced results similar within a single threshold range in a high proportion for each compound: for hydrochloric acid, 72.9% (N = 44); for quinine, 76.9% (N = 221); and for PROP, 76% (N = 225).

Correlations between thresholds for the different substances were positive and significant (N = 308): between PROP and quinine, r = + 0.44 ± .05 (p < .01); between quinine and hydrochloric acid, r = + 0.35 ± .05 (p < .01); between PROP and hydrochloric acid, r = + 0.17 ± .06 (p < .05).

In 3 out of 161 cases of thalidomide embryopathy seen in Hamburg, typical malformations of thalidomide causation were associated with cleft lip and/or palate. The same association was present in 6 out of 918 cases of thalidomide embryopathy reported by correspondence. Clefts of the face are more common in thalidomide children than in other children. Usually, they are associated with ear deformities. In cases of aplasia of the radius observed before the introduction of thalidomide but not in those connected with thalidomide intake, clefts are more common than in the general population. The association of clefts and ear deformities has been known before the introduction of thalidomide. Thalidomide is probably the cause of only some cases of association.

The first cellular differentiation in the process of segmentation leads to the embryonic period, the major organogenetic period for the nervous system. In man, it appears between the second and the eighth week after conception.

During the foetal and perinatal periods, the nervous organization mainly develops at the cerebellum and cerebral cortex levels. The cerebrum functional maturation continues well beyond birth.

Neuroblasts are the most widespread mother-cells in the developing nervous system during the embryonic period, but some are still to be found after birth.

Animal experiment has demonstrated that ionizing radiations were able to disorganize neurogenesis in any of its maturation stages, even at very low doses. It is possible to establish a chronological table showing the anatomical or functional deformities in relation with the embryonic age at which rays have been given.

It appears that in man the most dangerous period is between the beginning of the second and the end of the eighth week after conception. At that moment, pregnancy is often ignored and a dose of 20 to 40 r is sufficient to entail serious damages, such as microcephaly, protrusions of the brain or mental retardation. On drawing near to birth the foetal or neonatal nervous system of rodents or primates is still radiosensitive, especially at the cerebral cortex level and the consequences will be of a neurophysiologic or psychosensorial nature. Certain embryopathies or neurologic alterations would only be apparent in subsequent generations, following mutations induced into the mother-cells of the nervous system. Genetic deformities of the nervous system can also result from moderate irradiations of the gonads.

Further to the precise experimental research work on the radiovulnerability of the embryonic or foetal nervous system of the animal, certain clinical observations are presented, which lead to similar conclusions.

The atomic bombardments have caused numerous neurological trouble among the children who had been irradiated in utero. And the genetic effects are not yet perfectly known to-date.

This set of experimental and clinical data must prompt us to be very careful when using ionizing radiations, even at low doses, in pregnant women and newborn.

Male and female rats of three different strains were subjected to physical restraint, when it was demonstrated that there is a relationship between the strain of the rat and its susceptibility to gastric ulcer formation. Severity of ulceration was greatest in Wistar rats. Hooded Wistar rats were also ulcer-susceptible, but not to such a great extent as Wistar animals. Sprague-Dawley rats were resistant to ulcer formation. Sex differences in ulcer severity were found only with restrained Hooded Wistar rats.

The results of this investigation compare favourably with results published for individual strains of rats by other workers. It is possible that genetic influences may be responsible for the differences observed, but the way in which they operate is not understood.

Taste threshold for phenylthiocarbamide were studied among 242 Tibetans, 125 Spitians and 314 Lahaulis, the three Mongoloid populations of the Indo-Tibetan border. No statistically significant sex differences have been observed in the frequency of tasters and non-tasters in the present study. The frequency of non-tasters among Spitians (12.00%) and Lahaulis 12.73%) is strikingly similar and slightly higher than among Tibetans (10.74%). Statistically the difference in the three populations is non-significant (χ2 = 0.95, df = 2, p>0.05). In spite of the considerable Hindu admixture with a high frequency of non-taster gene, Spitians and Lahaulis have maintained a rather low frequency of non-tasters. This is true of populations all along the cis-Himalayan region, where similar Mongoloid and Hindu admixture has taken place. Besides the main Mongoloid element the proto-Australoid racial strain in the region may also be considered responsible for lowering the frequency of non-tasters.