A family is described with heteromorphism of N. 16 chromosome pair. The abnormal submetacentric chromosome was found in a total of 8 family members. Seven out of these carriers show a variable degree of myopia.

The authors examined the manner of clasping the hands (HC) and folding the arms (AF) in 415 unrelated pupils, aged from 9 to 15, of the Budapest school “Horváth Imre”. As refers to HC, 54.2% of the total material was found to be «L» (55.2% in ♂ and 53.2% in ♀), while concerning AF, 62.9% of the total material was found to be “L” (60.4% in ♂ and 65.5% in ♀). No significant difference between sexes could be observed. On the basis of a test constructed by the authors and supposed to be connected with handedness, every pupil examined was marked by a “point number for left-handedness” (PNLH). New observations drawn from our data are: (1) the PNLH average of right-handed pupils is somewhat higher in ♂ than in ♀ (2) a higher PNLH average is found, both for HC and AF, in the group of “L” individuals; (3) as the most striking phenomenon, the group of “R” type girls for HC (marked as “1”) contains a significantly high number of“absolutely right-handed”. This observation suggests that there may be a latent connection between HC, AF and laterality, but the lack of a simple and manifest coherence between these characteristics makes it inadequate to apply HC and AF as tests for handedness.

This paper reviews the investigations in the field of the effect of natural radiations on human populations, and discusses a number of problems inherent to retrospective genetic studies of human populations living under high levels of natural radiation. The solutions to face, at least partly, such problems are presented and discussed with special reference to the Brazilian “Projeta Espírito Santo” (PES).

In summary, the main PES subjects presented and discussed are as follows:

1) The data, including about 7000 couples and 40000 pregnancy terminations, have been fully collected and are presently under analysis. They were gathered from January to October 1961 by a team of specially-trained female interviewers employing a standard questionnaire, making home visitations, and being directly supervised by the present author;

2) The reporting has been practically consistent both within and between populations throughout the whole field work. Biased contribution both from the interviewers and the informants was probably negligible. The collection of the data was not subject to any subjective factor related to problems of radiation effect.

3) The interviewers came from the same socio-economic level from which the majority of the people interviewed belong. They were rather familiar with the region and had a perfect understanding of the culture of the people.

4) A checking survey was performed to estimate the reliability of the data, with good results.

5) No propaganda or publicity has been made preceding or during the field work. This reduced the probability that people and the field work team knew o our interest in radiation problems.

6) Although efforts were made to have good descriptions of the abnormalities, and good information on the causes of deaths, unfortunately accurate diagnosis was not possible.

7) Cultural and religious practices probably do not affect differently reproduction in the radioactive and control areas, and socio-economic conditions seem to be roughly similar.

8) It is difficult to know the cumulative radiation dose to the parents of the individuals analyzed (an attempt regarding this point will be made when the data are analyzed). The mean individuals living in the control, intermediate and radioactive areas are probably subject to minimal gonad-doses of about 2, 3, and 7 r in a 30-year period, respectively.

9) No attempt was made to study the influence of radiation on the rate of mutation at specific loci, but an analysis will be made of the genetic characteristics of the populations assumed to be conditioned or influenced by mutations at many loci.

10) As has been duly pointed out in this paper, the “Projeto Espírito Santo” (PES) was not specifically planned to demonstrate, with conclusive results, the genetic effect of natural radiation. Although some positive result is possible, it is highly improbable.

Cytogenetic examinations of a 7/12-year-old girl and her parents revealed a familial G/G translocation.

46 chromosomes in the mitoses of the mongoloid child and only 45 chromosomes in those of the apparently normal father could be observed. The analysis of karyotypes revealed a balanced G/G translocation in the father and a G/G translocation mongolism in the probanda. Dermatoglyphic patterns of both the child and her father showed some features characteristic of Down's syndrome.

The mother's karyotype proved to be normal (46, XX).

Three clinically atypical cases of Down S. and cerebral idiocy are described, showing peculiar chromosomal deviations and of difficult diagnosis. One more case is described, partly showing Marfan S. symptomatology with a duplication of the satellite-region of a G-Chromosome. This chromosomal deviation appears to occur in the family, although with no clinical significance.