Nel Decimo Congresso internazionale di Genetica il Comitato Organizzatore ebbe l'eccellente idea di dimostrare alla popolazione di Montreal, Canada, quale possa essere l'utilità pratica della Genetica e perciò aprì al pubblico una Mostra che portava questo slogan: «La Genetica a servizio dell'uomo» (Genetics in the Service of Man).

Se dovessimo anche noi fabbricare uno slogan come riepilogo dei nostri lavori, mi sembra che potrebbe essere il seguente: «La Genetica a servizio della Medicina».

Infatti i temi delle nostre relazioni, tavole rotonde, simposi e comunicazioni riguardano per 1/3 l'uomo sano e per 2/3 l'uomo ammalato. Del resto, come nella Medicina la conoscenza dell'uomo sano è naturale premessa per la conoscenza dell'uomo ammalato, così nella Genetica la conoscenza dell'eredità dei caratteri normali dell'individuo e della popolazione è, a sua volta, la necessaria premessa per la conoscenza della Genetica delle malattie dell'uomo.

La Genetica che si occupa di queste malattie porta un nome ormai introdotto e accreditato: «Genetica Medica». Il tema della mia relazione porta invece un nome diverso, quello di «Genetica Clinica», nome che io vorrei giustificare dinanzi alla vostra cortese attenzione.

The Committee of the Xth International Congress of Genetics had the excellent idea of acquainting the public of Montreal, Canada, with the practical utility of Genetics by organising a Public Exhibition under the slogan of: “Genetics in the Service of Man”.

If we were to choose a slogan that would best summarise our work at this Conference, I think we could suggest the following: “Genetics in the Service of Medicine”.

For one third of this Conference's papers, panel discussions, symposia and reports, has dealt with normal man, whereas two thirds considered diseased man. Just as, in Medicine, knowledge of normal man is the natural prerequisite for the understanding of human pathology; so in Genetics, knowledge of the heredity of normal traits, both of the individual and of the population, is the necessary prerequisite for the knowledge of Genetics of human disease.

Genetics dealing with disease now bears a name everywhere introduced and generally accepted: “Medical Genetics”.

The subject of my paper, however, carries a different name: “Clinical Genetics”, and I would now like to justify its choice.

The number of twins in 942 families where the propositus had a congenital malformation of the heart has been studied. The 38 pairs were not significantly more than could be expected by chance: nor were the 21 pairs where one member had a malformation of the heart. In 16 pairs, one was affected and the other normal; and in 5 pairs, one was affected and the other unknown. In 2 pairs, both were unknown because of early deaths; and in 15, both members of the pair were normal. In no pair were both members known to be affected.

There is clear evidence from this series and from the series of Uchida and Rowe (1957) and of Lamy et al. (1957) that where one member of a pair of monozygotic twins has a congenital malformation of the heart, the other is generally normal. It is the exception rather than the rule for both members to be affected, though several examples of such pairs have been reported.

There is some evidence from these three series that monozygotic twins are more liable to have a malformation of the heart than dizygotic twins and their sibs.

It follows from these two findings, that the immediate cause of the malformation of the heart must be environmental, though probably there is some genetic predisposition. A disturbance of the foetal circulation to the affected twin because of a single placenta and chorion seems to be the most likely environmental cause.

I should like to thank Professor Gedda of Rome and Professor Polani for their helpful suggestions and Dr. I. E. Evans for letting me see his unpublished paper on the evidence for monozygosity in some of the pairs of twins included in this paper.

Reproduction in mongoloids is a rarity. Allen and Baroff (1955) cite only four reports prior to 1949 which described such instances and Øster (1953) considered the diagnoses uncertain in two of those reports. At least seven more recent instances have been recorded (Le Long, Borniche, Kreisler, and Baudy, 1949; Sawyer, 1949; Forsmann and Thysell, 1957; Rehn and Thomas, 1957; Schlaug, 1957; Mullins, Estrada, and Gready, 1960; and Hanhart, 1960). In four of those cases the offspring were non-mongoloid and in three, mongoloid.

The case described by Rehn and Thomas (op. cit.) is the subject of this report. Because those authors were aware of the present comprehensive study, their diagnoses of mongolism were based on only routine clinical examinations. The purpose in making this investigation was to determine whether or not both the mother and her female offspring were mongoloid. Toward that end the mother and child were examined carefully for the presence of the various stigmata of mongolism. The results of those examinations are presented below.

The mother in the present case was living at home when 19 years of age and would probably not have been committed to an institution had she not become pregnant. She was committed with the diagnosis of mongolism and pregnancy three months prior to delivery and remained a patient at the institution until released on home parole a few months following delivery. Her child was committed with a diagnosis of mongolism shortly after birth and has never been away from the institution. Paternity is unknown, though the mother's father has been suspected.

The authors explain 9 cases of Bart's Hb. and one case of Hb. Alexandra, identified on 3.556 blood samples from the umbilical-cord in human newborn in time. Electrophorectical and spectrophotometrical examinations showed that Bart's Hb. is identical to Hb. H2 (the least fast of the two Hb. fractions present into the bearers of Hb. H).

In 7 newborn infants, it has been possible with Bart's Hb. to reexamine them, some months after they were born; it was observed that the said haemoglobins had disappeared; at the same time, in 4 of those subjects, a clear microcytemic picture was noted while in 3 others, still very small, the microcytemic picture appeared still uncertain. In 8 families with newborn babies with Bart's Hb., the two parents were also examined, and in 7 of these families one of the two parents presented a microcytemic picture; in one of them the hematologic traits were normal in both parents, except a very hight alteration of the eritrocyte morphology in the mother.

None of the examined parents presented any abnormal haemoglobin; furthermore, all microcytemic parents (except one) and all children with Bart's Hb. presented a normal rate of Hb. A2. This fact, absolutely similar to that observed in the bearers of Hb. H and in their microcytemic relatives, allow to put forward the hypothesis that Bart's Hb. and Hb. H appear in the same families in which we find that special type of microcytemia without any increase of Hb. A2, which would correspond to the microcytemia of the α chain.

In this work the results of a research on the consanguinity of populations living in the Lodigiano, the southern part of the province of Milan, are exposed and briefly commented.

It has been found:

1) a relatively low incidence of consanguineous marriages from the third to the sixth degree (uncle-niece and aunt-nephew, first cousins, first cousins once removed, second cousins and double relatives), which varies with the time and the number of inhabitants of the «comuni»: in the whole, from a frequency of 2,27% in the years 1900-1923 they have decreased to 1,54%, in the years 1933-1956;

2) correspondently low coefficients of inbreeding, being F 0,00101 in the first period and F 0,00061 in the second;

3) no negative correlation between the number of inhabitants of the «comuni» and the incidence of consanguineous marriages.

The marked difference between these results and that obtained for the other part of the province of Milan shows how great the variability of this phaenomenon is even in small areas; variability that should be accurately evaluated and taken into account for studies of population genetics.