A case of 8 trisomy syndrome, identified on the basis of the heat denaturation technique, has been detected in a patient with mental retardation, congenital malformations, and peculiar ocular anomalies. This observation confirms that, even without evidence of mosaicism, this chromosome does not seriously upset the viability of cells and could be less deleterious to the individual than trisomy 13, 18, or 21.

The mental development is not too much impaired and the skeletal abnormalities are mild, as compared to those found in previously reported cases. On the other hand, the cardiovascular system is involved and the ocular lesions are complex. They include prominent eyes, epicanthus, hypertelorism, antimongoloid slant of palpebral fissures, ectopia of lacrimal point, megalocornea, enlarged iridocorneal angle, subatrophic papilla, tortuosities of retinal vessels, absence of deep perception.

The case is described of a child who presented a slight psychomotor retardation and malformative signs, together with an XYY caryotype, and who died at the age of 7 years from a medulloblastoma, as could be later confirmed by autoptic examination.

The relations between chromosomal and neoplastic pathology are described.

A total of 105 sibships with one or more members affected by CNS malformations have been drawn from the Mendel Institute's Eugenic Counseling file and examined. The mode of inheritance and the variability of segregation have been verified according to the presence or absence of spina bifida occulta in one or both parents.

The results obtained lead the authors to suggest that the expression of major genes responsible for the pathology be conditioned by minor genes responsible for localization.

The results of a study on the chromosome association index carried out on a sample of singletons and on a sample of MZ and DZ twins, all of different age groups, lead to tentatively conclude that the reduced efficiency of mitotic genotypes, as reflected by the phenomenon of association, is genetically conditioned.

Blast index, mitotic index, and rearrangement index, have been assessed and compared in a sample of male MZ and DZ twin pairs belonging to two age groups: 10 and 60 years. For all three indexes, both the hereditary conditioning and age modifications could thus be confirmed.

A sample of sibships with two or more members affected by progressive muscular dystrophy has been drawn from the Mendel Institute's Eugenic Counseling file and examined with respect to the age of onset of the pathology (its clinical varieties being taken into account) in the members of the same sibship. Significant correlations have been found, thus suggesting the existence of characteristic ages of onset within each family.

A study of weight increase in the first year of life has been carried out on a sample of 50 MZ and 50 DZ twin pairs of both sexes, as compared to a similar sample of singletons. The results show that weight increase, as examined at different stages in the first year of life, undergoes significant hereditary conditioning (H ≃ 0.60).

Following previous application of mathematical models to the study of gene decay, as suggested by Gedda-Brenci's model of the ergon-chronon system, further results are reported, with special respect to a mathematical model of back mutations.

Personal examination of 39 cases of Fabry's disease, with special respect to a chronogenetical analysis, revealed interesting temporal features both in the age of onset and the age of death.

The results of a study based on(1) a sample of 9000 cases of psoriosis, (2) a more specific sample of 2000 patients of psoriasis with one family member also affected, and (3) a small sample of affected twins, lead to the tentative conclusion that disposition to psoriasis may well be the result of a differential time of decay of the genetic information.