An extensive review of the literature on sex differences in human intelligence leads to the conclusion that there is strong evidence for sex differences in processing both verbal and spatial information. The few genetic studies that there are all point toward a sex-linked mode of inheritance of certain spatial abilities.

A sample of 47 MZ and 49 DZ pairs of Brazilian twins was investigated in relation to school achievement in six specific areas of study, as well as performance in the test of Dominoes, the Differential Aptitude Tests (DAT) and Griéger's Characterological Questionnaire. Significant F-ratios (variance within DZ/variance within MZ) were observed for the school grades obtained in five of the six areas considered, as well as for their general average; the same being true for the results on the indicated measure of general intelligence, six of the eight DAT tests, and two of the characterological elements. There is a clear positive relationship between the grades earned by the twins and their performance in the Dominoes test. Achievement in Portuguese and foreign language correlates positively with DAT's Sentences; and achievement in mathematics correlates positively with DAT's Numerical Ability, Abstract Reasoning, and Clerical Speed and Accuracy. The results show an agreement with previous estimates of the genetic determination of these variables, which is to a certain extent surprising if we consider the differences in sample sizes, age, and degree of schooling of the subjects, environmental differences, and the dissimilarities which exist between the homes and school systems of USA, Europe, and Brazil.

A sample of 71 twin pairs (32 MZ, 39 DZ), of mean age 9.7 years, has been studied through various techniques in order to better understanding the interpersonal relation of twins, both within the pair and with respect to the members of the family group, and especially the mother. Zygosity, dominance, and birth order have been taken into account. The relation between MZ twins appears to be somehow less special than believed, whereas a special triadic relation appears to exist with the mother. A differentiated research of identity in MZs and autonomy in DZs is also noted (which contributes to a better understanding of problems of schizophrenia in twins). Finally, the relation between MZ cotwins shows mutual similarity and attachment to be lower than foreseen and, anyhow, of a far from misterious nature.

The significant differences in biochemical and chromosomal characteristics, and familial history observed between group of mothers who gave birth to children affected with G1-trisomy (Down's syndrome) and their age-matched controls, indicate that these three maternal variables, in addition to the well known variable of maternal age, are associated with etiology of the aneuploidy. Since attempts to find statistical correlation between these chromosomal and biochemical variables failed, it is believed that these three are unrelated, but very possible etiological factors.

A selective loss (or a blocking) of rRNA genes in ageing oocytes, and its compensation through the retention of an acrocentric nucleolar organizer chromosome, is proposed as a possible mechanism responsible for the increased frequency of Down's syndrome with maternal age.

A number of facts that cannot be interpreted in terms of nuclear genes would seem to be interpretable in terms of cytoplasmic heredity. The hereditary role of the mitochondria has already been demonstrated in molds. The role of the cytoplasm (matrilineal heredity) has also been shown in some phanerogams, and analogous facts have been noted in insects and molluscs. In amphibians, the influence of an alteration of the egg cortical cytoplasm has been shown to reappear in the following generations. This cortical cytoplasm includes the morphological plan of the organism with its bilateral symmetry: mirror imaging in monozygotic twins would only be an extension of bilateral symmetry. In Tatusia novemcincta the twins may be morphologically or chemically different, which may only be explained by an unequal subdivision of a heterogenic cytoplasm. Similar facts are observed in human twinning. Monozygotic twins are usually discordant with respect to congenital malformations (especially symmelia and anencephaly), which may only be interpreted in terms of unequal distribution of cytoplasmic properties.

A human thoracopagus of slightly unequal twins having a common umbilical cord with exomphalos is described, with special reference to the cardiovascular system. The larger twin had single umbilical artery. The smaller twin had a large left umbilical artery which was in direct continuity with the aorta, a small right umbilical artery with sole connection to the right external and internal iliac arteries (right common iliac artery was absent), missing umbilical vein, a rudimentary nonfunctional heart with atresia of the truncus arteriosus, and a right-sided aortic arch. Exomphalos of both twins is accounted by the possible defective growth of umbilical mesoderm caused by abnormal umbilical vessels. Reversal of systemic circulation in the upper part of the body of smaller twin is discussed. The importance of a careful study of umbilical veins is emphasized.

The effect of a given concentration of TrenimonR (6 × 20−8 mol/1) on the lymphocytes of 11 healthy subjects with morphologically abnormal karyotype was analysed in vitro. The research included 6 subjects with balanced translocations, one of them with a centric fusion. Of the remaining 5 subjects, 2 had a duplication in the paracentric region, 1 showed an inversion, and 2 had a marker chromosome.

In the group with morphologically abnormal chromosomes a higher sensibility to the influence of TrenimonR was found as compared with a control group with morphologically normal karyotype. The subjects with an atypical karyotype had 36 to 65% aberrations, the control group 28%. A localization of the breaks showed no increased aberration rates in the morphologically abnormal chromosomes.

The dermatoglyphic analysis of a group of Italian patients with Cooley's anemia and Cooley's trait shows Cooley's anemia patients to undergo a significant increase of loops on fingers and a corresponding decrease of whorls. The total loops frequency correlates negatively with the ridge distribution per loop and the total ridge count is significantly decreased. The atd angles are larger. Minor changes in the distribution of patterns in the thenar and hypothenar areas are also observed. In the Cooley's trait patients, loops on fingers are more frequent than in controls, but no difference with Cooley's anemia series is observed. The above findings suggest that the gene(s) controlling loops formation in linkage disequilibrium with thalassemia mutant may have been favourably selected on the “thalassemia chromosome” in the malaria environment.

The risk of having a child affected by isolated congenital deafness (or deafmutism) is high, if the two parents are affected, if only one parent is affected, but belonging to an affected family, and if the couple has already an affected child.

A computer system analysing human metaphase images and finding banding patterns of R-banded chromosomes has been set up. This first paper describes the interactive procedure in selection of metaphase images, automatically digitized starting from microphotographic negatives.

Two unrelated patients with trisomy 2q32 → q37, resulting from maternal balanced translocations t(2; 13) (q32 q33) and t(2; 15) (q32 q26) are reported. Comparison of the clinical findings suggests that trisomy 2q is associated with a rather characteristic constellation of symptoms and malformations.

A case of “G 2 Deletion Syndrome” is reported, based on concordant cytogenetic, clinical and dermatoglyphic findings. The definition of the syndrome, as associated with either a ring or a partially deleted chromosome 22, is discussed. The resulting interpretation favours the hypothesis of deletion of the short arm extending into the centromere.

A modified centromeric heterochromatin banding technique using barium hydroxide octahydrate is described. The relationship between slide maturity and time of denaturation by barium-hydroxide is discussed.

Intraclass correlation values have been studied in a sample of 50 MZ and 50 DZ twins with respect to fourteen palmar dermatoglyphic metric traits in binary combinations. The results confirm the general trends already shown in singleton studies. The shape of the palmar surface does not appear to be significantly correlated with other metric traits. Generally speaking, a large independence has been found between the various traits.

The wide fluctuations of the three angular measurements, a-d, PMPC, and DWC with longitudinal axis make palmar projective breadth (PB) the ideal standard axis for any work involving the quantitative estimates of longitudinal and transverse trends of palmar triradii.

A peculiar type of hypodontia is described in two opposite sexed siblings and considered to be inherited as an autosomal recessive trait

The levels of the two enzymes, GAL-1-PUT and GAL-KIN, have been examined in a sample of 35 MZ and 45 DZ twin pairs of both sexes. The activities of these enzymes do not appear to be influenced by sex. The role of genetic factors appears to be rather limited in the case of GAL-1-PUT, but much higher in the case of GAL-KIN.

Gm and Inv polymorphism has been investigated on a sample of the general Greek population (N = 256) and on a sample of the Achaia population of Northwestern Peloponnesus (N = 150). The estimated frequencies were, respectively in the two groups: Gm1, 0.156 vs. 0.180; Gm1,2, 0.010 vs. 0.017; Gm4,12, 0.834 vs. 0.803; Inv (+1), 0.125 vs. 0.140.