Mitotic induction in human circulating leucocyte cultures has been studied by the twin method. The study of this phenomenon in 20 individuals belonging to 5 MZ and 5 DZ twin pairs shows that its variability depends on the adopted dose of phytohemoagglutinin, and not on the individual genotype, nor on the characteristics of the single pair, or type of zygosity.

The Author deals with the problem of morbid disposition from the genetic standpoint. He further reports and discusses the results obtained by studying 447 pairs of tuberculous brothers, as far as the age of onset, the clinical form and the localization of the tubercular process are concerned.

Data are also reported concerning the morbidity of silicosis among 683 Sardinian mineworkers, especially concerning its frequency in the families of both affected and healthy propositi, for a total amount of 9,127 individuals examined. The results are also shown of a wide survey carried out on 293 single-born and 2,474 twins, concerning the following allergic diseases: eczema, asthma, urticaria and hay-fever. The possible mechanism of inheritance of morbid disposition is also discussed.

First of all the Authors stress the importance of twin studies as a method of analysis of the pathological phenomena from a hereditary standpoint: to this aim, the Interzygotic Twin Method may be used in statistical studies, and the Clinical Twin Method in clinical ones. On this basis, the Authors report their observations, on a remarkable number of male twin pairs, affected by anomalies or syndromes including one or more genital dysfunctions, either in infancy or adolescence. Numerous cases of phimosis are thus presented, where the higher concordance in pairs of MZ twins stands for a hereditary conditioning; cases of hypospadias, showing a perfect symmetry of the malformation in the cotwins; cryptorchism, with various possibilities of presentation of the anomaly in the intrageminal comparison. The Authors also describe in detail, making an analytical intra-pair comparison of the symptoms and laboratory data, some cases of complex adiposogenital dystrophy, as well as one case of Laurence-Moon-Bardet-Biedl syndrome with different clinical manifestation in a DZ pair. The longitudinal study carried out over many years on some of the pairs affected by the above mentioned clinical pictures, and the clinico-statistical analysis of the cases under consideration allow the Authors to draw a number of positive conclusions concerning the variable, genotypic conditioning of the sex anomalies considered: in this field, as well as in many others of nosography, the Clinical Twin Method appears to be highly useful in practice, and unique by reason of its peculiarity.

In the course of a research work based on the study of the thrombelastogram in 20 male and 20 female MZ pairs, and in 20 male and 20 female DZ pairs, the Authors have evaluated the genetic impact on the thrombelastographic traits. The analysis of the experimental data shows that the following data are especially genetically influenced:

1) the maximum width (¾)

2) the elasticity modulus ()

3) the time r (½)

4) the thrombelastographic index (½)

1. Histological studies on the developing retina in mice, rats and Irish setters affected with a hereditary retinal degeneration of the retinitis pigmentosa type do not lend any support to the view that the retina is fully developed before degenerative changes set in — as postulated by the conception of abiotrophy. In fact, the retina in these animals, though reaching functional maturity, lacks the final histological differentiation that leads to fully developed rods: the rods are present, but they are rudimentary and do not survive for the normal span of life. These studies suggest that the abiotrophies (or heredo-degenerative diseases as they are sometimes called) are in fact the mildest of congenital defects and do not therefore stand in sharp contrast to congenital abnormalities.

2. Clinical studies on the hereditary affections of the retina show that the distinction between congenital non-progressive disorders and abiotrophic progressive disorders is not valid. Most congenital abnormalities of the retina such as macular cyst, retinal aplasia, asymptomatic macular defect and congenital sex-linked detachment, show a considerable post-natal course. In fact it is difficult to find a clear example of a congenital non-progressive retinal anomaly. In the choroid, the one substantial congenital defect — macular coloboma — is non-progressive.

3. By definition all abiotrophic defects have a progressive course. This, however, varies considerably in the different affections. In the retina, retinitis pigmentosa represents not one disease but a whole series of affections. This is seen from such well differentiated types as the recessive, dominant, recessive sex-linked and intermediate sex-linked varieties. Furthermore, in different families there are different associated anomalies, such as glaucoma, cataract, ophthalmoplegia or macular dystrophy. Unilateral retinitis pigmentosa appears to be a somatic mutation. The macular dystrophies are likewise a group rather than one disease, as shown by the different genetic behaviour and the different clinical features of the recessive, dominant and sex-linked varieties of macular dystrophy. Furthermore the ophthalmoscopic reaction ranges in different families from fine granular changes to fairly heavy pigmentary changes, or whitish lesions of the exudative type. In the choroid, choroideremia and choroidal sclerosis — with its generalized, central and peripapillary types — are the two outstanding abiotrophic affections, with markedly dissimilar clinical behaviour.

4. An important abiotrophic affection coming on in middle age is dominant generalized fundus dystrophy with its stormy onset, oedematous and exudative reactions at the macula, and ultimately extensive atrophy throughout the fundus. This has to be distinguished from another dominant affection with a much milder course — Doyne's choroiditis. The choroidal nature of these two affections is not definitely established. They may possibly both be disorders of the membrane of Bruch.

5. Retinoblastoma appears to occur in both a genetic and non-genetic variety. It is likely that the bilateral case represents a germinal mutation and that the unilateral case is generally a somatic mutation; only the germinal mutation is, of course, transmitted.

6. A number of other affections may have a genetic background as yet ill-established.

An unusual case is described in which a man was accused of the paternity of a child, and an expert reported him to be type RhzRh1, the mother as type Rh1rh and the child as type Rh2rh, thus excluding paternity. In repeat blood tests, the author confirmed the typing results on the putative father and the mother, but showed the child to be type Rhzrh instead of type Rh2rh, so that paternity was not excluded. Instead, the presence in both putative father and child of the rare gene RZ (or ry) could be considered circumstantial evidence that the accused man actually was the father. It is pointed out that the error could easily have been due to the mistaken use of anti-rhi serum in place of anti-rh′ serum. Such an error would be more apt to occur with a worker using the fallacious C-D-E notations, because the tacit assumption implicit in those notations that each agglutinogen has but a single corresponding antibody (and blood factor) would render unthinkable the concept of more than one kind of anti-rh′ (anti-C) reagent.

A detailed description is given of the study performed in a pair of monozygotic Negro twins both suffering from hemophilia B; the bibliography is also reviewed about the occurrence of hemophilia in twins. The zygosity determination was performed utilizing anthropometric measurements, observation data, finger and palmar prints, seven systems of blood groups and five other genetic systems. The twins present a great similarity in the hemorrhagic symptoms, coagulation tests and Christmas factor level, but morphologic and physical differences due to the disease. These differences are explained by the diversity in the medical-hospital care which both received.

The Authors have analyzed the data concerning length of gestation and neonatal weigth and length measurements in 2,440 living twin pairs (from the files of the Mendel Institute), in order to verify the frequent assumption that all twins should be considered as prematures and, as such, affected by congenital debility.

Comparing their findings with the standard values for prematures, they reach the conclusion that the majority of twins who have survived the perinatal period were not prematures. Furthermore, the less developed among such twins differ from single-born prematures by reason of their subsequent normal auxologic development, whereby the Authors propose that they should rather be considered as “premature-like”.

A study has been carried-out on familial glioma, according to various data, both personal and drawn from the literature. The statistic evaluation indicates, at least in part, a probable hereditary conditioning. Out of 393 cases of glioma, three have been found to be familial, which is much more than it would be expected on the basis of statistical evidence. This should be taken into account in the evaluation of the origin of tumours.

A female baby, showing the characteristic malformation pattern of the 17-18 trisomy syndrome, was found to have two extra chromosomes in groups 6-X-12 and 17-18, respectively: the presence of double drum-sticks and of double Barr bodies leads to interprete the karyologic finding as a triple-X + 17-18 trisomy. Autopsy showed an interventricular septal defect and an abnormal histological structure of the ovaries.

A child, aged 11, with female phenotype, associating a sacrococcygeal agenesis to Bonnevie-Ullrich's syndrome, without gonadal dysgenesis, is described. The patient's caryotype is a normal female one (44 A, XX). No similar cases could be found in the literature.

This association of two syndromes of undetermined origin is probably fortuitous. A genetic study of 65 pedigrees from the literature did not reveal a mendelian type of inheritance. The possibility of external factors having occurred during embryonic life is discussed.

The authors briefly describe their old and recent research work on the etiology of leukemia, and discuss the genetic-viral hypothesis of human leukemia. The injection of human leukemic blood in fertilized chicken eggs, before incubation, causes a severe disease in the embryos. This disease is characterized by the fact that the hemoblasts are extremely atypical, and loose the ability to produce intravascular blood cells, while they form perivascular infiltrates. The disease is indefinitely transmitted from egg to egg, also using acellular filtered material. The transmissibility is inactivated by heat. In conclusion, we can say that the observations described strongly support the viral etiology of human leukemia and suggest the hypothesis that the virus might be responsible for a somatic mutation of the blasts.

The occurrence of symmetrical and asymmetrical combinations of termination of the palmar main lines has been studied. Symmetrical combinations are of the same type, while asymmetrical ones are of different types. Actual frequencies (AF) and chance frequencies (CF) of various combinations have been calculated.

1) Though various symmetrical combinations are found on palmar main line D, combinations 11/11 exhibits a higher frequency in both sexes. Similarly, palmar main line C shows a higher frequency of combination 9/9 in both sexes. Palmar main line B is remarkable for the absence of combination 3/3, while combination 7/7 is the most common. Palmar main line A is also remarkable for the absence of combination 1/1, while the most common combination found is 3/3.

2) The higher value of the AF-CF ratio shows a greater tendency to symmetrical combinations.

3) A strong tendency of repulsion is observed on the part of symmetrical combinations.

4) Chance frequencies (CF) can be calculated provided that the termination frequencies of various palmar main lines are known.

5) The value of AF-CF ratio is inversely proportional to the value of chance frequency (CF).

6) In all symmetrical and asymmetrical combinations examined with the ‘t’ test no statistical significance has been found in either sex.

Duodenal ulcer is a rather common disease, showing a clear family concentration. The aim of this work was to detect, in the etiology of this disease, possible genetic components, and to study their characteristics. The survey has been carried out by analyzing the data collected in 100 families, assembled by starting from a corresponding number of « index cases », and utilizing for comparison and also further analyzing the data by Doll and Buch (1950) and by Doll and Kelloch (1951). The " secondary cases " found, as a whole, were 109 (90 males and 19 females). The results may be summarized as follows:

1) the frequency of the disease in the sibships, independently from sex and corrected for age, is of 32.5% ± 2.5;

2) the frequency is, however, different in the two sexes. The estimate of this difference has been obtained calculating the relative risk (x) to contract the disease in the males, as compared to the females. Considering all the families together, such risk is x =5.8. However, x =16.7 in the 39 families with both healthy parents; x = 4.0 in the 45 families with the father affected; x = 2.9 in the families with the mother affected;

3) though the analysis of segregation ratios would not allow, by itself, definitely excluding the hypothesis of a monofactorial recessive inheritance, many reasons lead to think of a possible case of « simulated mendelism »;

4) the application of the methods of analysis proposed and worked out, in their theoretical basis, by Penrose (1953) and by Edwards (1960) for the genetic study of common diseases, makes much more probable the hypothesis that the genetic basis of duodenal ulcer is multifactorial. This does not exclude, however, that some particular environmental factors may increase the phenotypical correlation among the brothers — at least in the material under consideration.

Therefore, the hypothesis now allowing the best interpretation of the observations is that duodenal ulcer could be controlled by a number of additive genes with a weak effect.

The Strong Vocational Blank inventory was administered to 43 pairs of identical and 34 pairs of fraternal twins in high schools in the Metropolitan Detroit area, and scores obtained on 44 vocational preference scales and 3 personality scales. F tests of the ratio between fraternal and identical within twin pair variances were significant beyond the .01 level of significance for the scales for Physicist, Mathematician and Osteopath while 9 more scales had F-ratios significant beyond the .05 level; these were for the scales of Dentist, Personnel Director, Veterinarian, Sales Manager, Aviator, Chemist, Public Administrator, Engineer and for the scale of Interest Maturity. Thus a total of 12 scales had F-ratios indicative of some hereditary contribution to the within pair variance of the twins in this study.

A comparison with the results published by Carter in 1932 was possible for 21 scales, by computing intraclass correlations for the present data. From these, as well as from the intraclass correlations reported by Carter, h2 values were computed and compared. There was stronger evidence for hereditary components in the earlier study, and the rank order correlation for the h2 values in the two studies was only .16, although in both studies it was found that the “Science” group of interest scales had the highest “average” h2 value (computed from average intraclass correlations, after Z-transformation).

These results are interpreted as indicative of a small but persistent contribution of hereditary components to the vocational choices reflected in scores on the Strong Vocational Preference Blank, particularly for scientific careers.

The use of the male form for the female twins in this study seems partly justified by the presence of equally often high mean values on scales and higher heritability estimates on some scales compared with the boys.

A case of monochorial and monoamniotic pregnancy is described. Of the four products of conception, two were apparently normal (stillborn) and two were monsters.

On the basis of current classifications, the latter two can be defined one as acardiacus acephalus and the other as acardiacus amorphus. After presenting the data resulting from all the investigations carried-out (radiography, sex chromatin, histological examinations, injection of the placental and foeto-placental circulation) the etiopathogenetical factors to be examined in determining congenital serious deformities are discussed in relation to the case under examination and on the basis of the most recent findings.

Two etiopathogenetical hypotheses are then suggested, resting on the supposition of a genie lesion which directly conditions either the subdivision into several embryos following ontogenesis or the « monstruosity » of the placental circulation.

On the basis of the results obtained it can be held that further discoveries on the subject will derive from genetics and experimental embryology.

The Anglo-Indians of India have been tested for the Tasting of P.T.C. The frequency of non-tasters in general shows that the population is intermediate between the European and Indian frequencies. They show a rise in the non-taster gene frequency with the rise in the dosage of European ancestry in their parentage.

The Mendelian law has further been established among the hybrid group as far as the frequency of non-taster gene frequency is concerned. In general the Anglo-Indians have 28.12 percent non-tasters of P.T.C., which shows a comparatively higher shifting towards the Indian range of values than towards the European one. It is explained to be due to the later practise of the Anglo-Indians to take in Indian brides, thus diluting the hybrids in favour of the base population.

The Indian populations of the State of Santa Catarina, Brazil, are found in two places, Duque de Caxias and Xapecó. In the former live Aweikoma (possibly a Caingang subgroup), Caingang and Guarani; in the latter, Caingang and Guarani. The Aweikoma intercross freely with the Caingang, and the Aweikoma/Caingang group thus formed can be compared with the Caingang of Xapecó. The Guarani, on the other hand, are reproductively isolated from both populations. The Aweikoma/Caingang of Duque de Caxias and the Caingang of Xapecó differ from each other in characteristics related to racial composition (degree and amount of non-Indian genes), gene flow, average age of mothers and frequency of stillbirths. On the other hand, they show similarities in a series of demographic variables related to fertility, mortality and inbreeding levels. The index of total selection intensity is practically the same in the two localities.

Present status of genetic and anthropological knowledge concerning haptoglobins, and report on the results of a survey carried-out on 141 subjects from Campania: Hp 1-1, 15 (10.6%); Hp 2-2, 60 (42.6%); Hp 2-1, 66 (46.8%); gene Hp1, 34.1%, gene Hp2, 69.1%.

Furthermore, a geographical peculiarity of haptoglobins is stressed, i.e. a rise in the frequency of the Hp2 gene from Westward to Eastward.