The introduction of informatics in the study of hereditary diseases, i.e., the birth of informatic medical genetics, marks a turning point in the history of medicine.

The biological informatics is the product of molecular genetics on one hand, and cybernetics on the other. The former has brought the study of the hereditary phenomena to the level of nucleic acids; while the latter, originally devised to the service of automation, reflects a number of fundamental biological phenomena, also at the molecular level.

The informatics of hereditary diseases is referred to a damage of the operative units acting to secure the development and homeostasis of the organism. The mechanistic conception of the damage is complemented by the energetic and chronologic concept.

On such foundations a modern conception of the genetics of diabetes is thus formulated. The clinical inadequacy of the static genealogical model is stressed, and the introduction of a dynamic model is suggested, taking into account the gradual chronological extinction of the normoglycemic genotype.

The following problems are briefly mentioned and discussed in this paper: (i) the role of genetics in public health, both in developed and in developing countries; (2) genetic aspects of the differential geographical distribution of diseases; (3) clinical and etiological aspects of malformation syndromes; (4) nosological complexity and phenotypic spectrum of these syndromes, with special reference to ectodermal dysplasias; (5) some problems of modern human communities.

An account is given of a family identified by a newborn malformed male. The chromosome anomalies described are interpreted as indicating that the father has a balanced translocation with a reciprocal exchange between no. 9 and no. 12. The supernumerary chromosome resembling a group F element, which is found in the propositus, is in fact one of the two rearranged chromosomes present in the father. The propositus therefore is trisomic for part of no. 9 and no. 12. His brother has a normal karyotype. Possible meiotic situations leading to the formation of the observed karyotypes are discussed.

A fluorescence staining method of the male chromatin body in human interphase nuclei is described.

A total of 1, 041 syphilis patients of both sexes and different ethnic origin (Chinese, Malay, and Indian) were investigated for the distribution of ABO blood groups and haemoglobin genotypes. There was no significant difference in the incidence of ABO blood groups and abnormal haemoglobins between disease and control series in any of the racial groups.

From the above series, 819 male patients were investigated for the incidence of G6PD deficiency. There was no significant difference in the incidence of this genetic marker in disease and normal series.

A survey of Gc and Hp polymorphism in Poland, designed to check results of earlier studies, gives the frequencies of Gcl and Hpl genes as 0.73 and 0.37 respectively.

In order to test if arm folding is a hereditary trait, 319 couples of parents and their 897 children have been examined. The distribution of the two phenotypes, D and G, is different from a O.5-0.5 distribution. No influence of sex nor age is observed. The matings are random and the mean number of children per family is the same for each type of mating.

The analysis of family data does not prove the hypothesis of a hereditary transmission of the trait, and important discrepancies are noted between observed values and those expected for genetic mechanisms with two alleles, D and G, of an autosomic or sex-linked gene.

Variations in skin color and palm patterns were investigated in two families in which the fathers are of mixed Negro-White origin and the mothers are Dutch. Segregation among the children indicates that two genes with cumulative effects are responsible for dark shades of skin in family A, whereas only one gene is responsible for dark skin in family B.

In family A the mother is heterozygous for accessory triradii and vestigial patterns in distal palmar areas, whereas in family B the father is heterozygous. Skin color and patterns in distal palmar areas do not occur independently among the children in family B, suggesting the possibility of linkage.

A study of the anatomical correlation for the fifth-finger ridge count and its ratio to the correspondent correlation of a first degree relative (i.e., between sons and fathers and daughters and fathers) has been carried out in an inbred population of German ancestry living in Northern Venezuela for the last 127 years. This study revealed a remarkable straight relationship of the logarithm of the above ratio to the probability of having both genes at the locus (or loci) identical by descent, for the trait fifth-finger ridge count, i.e., the coefficient of inbreeding. The practical consequences of this finding for the estimation of inbreeding, if confirmed for other populations, are emphasized.

The heritability of two main line indexes (DLI and TLI), a palm crease index (API), and an ulnarity index (UI) were investigated by using twin pair methodology for quantitative traits.

The analyses of the data allow to conclude that both DLI and API, which have been used to evaluate the obliquity of the main lines and the distal crease of the palm, should not be considered as depending upon an important genetic component. Otherwise, data on TLI and UI, while showing inconsistencies with the theoretical expectations, may be considered as genetic traits.

In Hungary the frequency of multiple births has been decreasing. In 1920 the rate of multiple births was 23-5‰; by 1968 this rate decreased to 18.2‰, i.e., only 77% of the 1920 data. The male preponderance in twin births is lower than in single births, and in triplets actually a female excess can be observed. Furthermore, it can be observed that there are more boys than girls among the first-born of multiple births. The average birth weight of liveborn and stillborn twins, and of liveborn triplets is 2101 g, 1458 g, and 1723 g respectively. The ratio of MZ to DZ twins is about 30:70 in 1968. The frequency of DZ twin births increases with maternal age (the peak is now over 40 years) and birth order. According to the 1959, i960, and 1968 figures, both DZ and MZ twin births were significantly more frequent in mothers aged 16 or less than in mothers aged 17-19 years.

This demographic survey belonged to preparatory works connected with the setting up of the Budapest Twin Register which came into force on January 1st, 1970.