The phenomenon of life, in its individual and collective expressions, develops through a sequence of times resulting from the interference of biological with physical time. While physical time is uniform, the biological one differs from one individual to the other, except for MZ twins.

The problem of biological time has been studied in physiology and informational genetics from the viewpoint of its succession of single times, although irrespective of the individual variability in their duration. This variability has already been shown by the authors to be hereditary, its inheritance being directly connected with the hereditary unit.

Biological time corresponds to the duration of degradation (“chronon”) of the energy of stability (“ergon”) possessed by the gene and, by extension, to the total chronon of the genotypes underlying a given structure or function. Ergon and chronon are correlated index values, thereby constituting a system (“E/C system”).

The individual variability of biological time depends on the A-T/G-G ratio in the DNA molecule, on the different amount of genie redundancy and on the different possibilities of repair of corresponding genes. The variability of these or possibly other causal factors determines the stability with respect to the environment in which the information operates, and especially to mutagenic agents.

The authors apply the E/C model to epidemiologic data concerning diabetes, lupus erythematosus, and peptic ulcer, and verify the consistency of the experimental data with the theoretical model.

Inbreeding effect revealed as mortality and morbidity in general may be ascribed to deleterious mutations generally present at different loci of the ancestors common to each consanguineous mating. A new coefficient (E) is suggested to measure this effect. On the basis of this theory, a new method to estimate the load of mutations disclosed by inbreeding has been presented elsewhere, and is now extended. In this method, the load is estimated without introducing gene frequency notions. Genetic loads estimated through our method are in rather close agreement to those estimated through the classical theory of Morton, Crow and Muller (MCM).

A family investigation has been carried out on 301 consanguineous and the same number of nonconsanguineous couples, who married in Florence in the years 1939 through 1958. The sample turned out to be homogeneous as regards age of the couple, year of marriage, period of cohabitation, social level, and methods of survey.

The average rate of consanguinity in Florence in the above years was of 0.458 × 10−3, with a decrease from 0.595 to 0.327 × 10−3 between the first and the second decade.

While the number of pregnancies is not significantly different in the two groups, abortions are more frequent among blood relatives. As a result, the number of stillbirths being not significantly different, the birth rate is higher among the controls. Infant mortality is more than double in blood relatives. As regards morbidity, hereditary defects or anomalies show an average increase of 2.6 times in the offspring of blood relatives: the increase being higher for serious hereditary defects (3.44) than for lighter ones (1.98). The finding of slight delays in mental development was 4.8 times more frequent in the offspring of blood relatives.

By applying Morton-Crow-Muller's formula, it was possible to calculate the A and B values, and to find out, in the observed population, the presence of 2.2-2.4 pathological gene equivalents per gamete as to early mortality (abortions + stillbirths + infant mortality); 1.6-1.7 gene equivalents as to hereditary defects in general; and 0.82-0.85 gene equivalents as to slight delays in mental development.

Sera from 50 mothers of G1-trisomy affected children and from 50 age-matched mothers, whose offspring included no chromosomal-aneuploidy affected children, were tested for presence of antinuclear antibody factors and nuclear staining with human squamous epithelium and with mouse liver. Consistently, more of the mothers of G1-trisomy affected children included positive findings in both tests, compared to the age-matched mothers.

A kindred is described with a probably new inherited syndrome, involving bilateral congenital hip dysplasia with coxa vara, patella aplasia and tarsal synostosis. This association is probably inherited as an incomplete dominant trait, apparently as a result of a new mutation.

In this case a single pleiotropic gene might be held responsible for the multiple skeletal defects.

From a bibliographical review, it may be concluded that the nosological association of these multiple defects has never been published so far.

A case of OFD syndrome in a male is reported. The clinical features are described in detail. The genetical aspects of the syndrome are discussed on the basis of the analysis of 33 families from the recent literature. It appears that in the great majority of the cases so far known, the syndrome is due to a dominant probably X-linked gene, lethal in males and with complete penetrance in females. Of all cases 24% are sporadic. It seems likely that a few cases are due to a recessive autosomal gene. It is concluded that the reported patient is, with high probability, either a mutant or a case with hereditary recessive pattern.

The authors studied the structure of the umbilical cord in a cephalothoracopagus and a holoacardius amorphus. In both cases they met with the absence of one umbilical artery. They discuss on the possible teratogenic influence of this umbilical anomaly, which appears in the acardius as a regular phenomenon, and, along with the velamentous insertion and with the vascular anastomoses bringing about the reverse blood circulation, constitutes the main cause of malformation.

Agreement prevails that MZ twins have higher concordance rates for cancer than do DZ twins. The exact genetic influence on concordance remains doubtful. Neither the patient groups nor the means by which data are analyzed are comparable. The naturally higher perinatal mortality rate among twins affects statistical analysis of diseases among surviving cotwins. Classification of zygosity among all studies of twins is not entirely reliable.

A review of published reports of cancer among twins notes concordance in a variety of tumors. Genetic factors appear to operate either in the concordance of the cancer or in the site of the specific tumors. A genetic origin of tumors in MZ twins is possible. Tumors, including type, site, and age of onset, affect MZ twins more than both members of a DZ pair.

Computerized permanent twin registers should be established for study of prospective follow-up of large twin populations. Suggestions are made for implementation.

A twin population model is proposed, and two different definitions of the rate of concordance are investigated within the context of this model. It is found that the statistic formed from the ratio of the number of affected twins that come from concordant pairs to all affected twins has certain advantages over the traditional definition of the rate of concordance. This twin population model is extended to nontruncated sample of twins. The parameters of this situation are estimated. Finally, it is shown how these parameters relate to the two usual estimates of the proportion of DZ. twins in a twin population, and the efficiency of these methods is computed.