Section 15 — Human Genetics 



15.38. The Torus Palatinus. C. Maximilian, Ioana 

 Popovici and R. Popescu (Bucarest, Rumania). 



Investigations concerning the incidence rate 

 of the torus palatinus in vaiious races have led 

 to the conclusion that this structure is a racial 

 character. This would account for the different 

 figures recorded in the populations studied. 

 Hereditary transmission is considered to be either 

 of the autosomal dominant or of the sex- 

 linked type. 



We have investigated the incidence rate of 

 this character in our country during the course 

 of history, from the neolithic age up to the pre- 

 sent. In order to determine the figures prevailing 

 at present, we investigated a number of 1000 

 skulls and two additional series, one intensely 

 exogamic, and another endogamic one formed of 

 20 families comprising 156 subjects from an 

 isolate in the Carpathians. The incidence rate 

 of the torus was found to range from 26 to 

 46 per cent, in all the series investigated, with the 

 exception of the isolated group, in which it at- 

 tained 75 per cent. These figures are similar to 

 those prevailing in peri-arctic groups. The for- 

 mation is already apparent during the first years 

 of life. Its development is genetically determined. 

 In the isolate it was often found to be of consi- 

 derable size (3rd degree) and clearly detectable in 

 7- or 8-year children. It is not yet clear whether 

 this large size is determined by a homozygotic 

 condition or by other causes. The type of trans- 

 mission appears to be autosomal dominant, 

 the incidence rates of the character being almost 

 the same in both sexes. 



The part played by heredity was further con- 

 firmed by the investigations of 7 pairs of mono- 

 zygotic twins who were all found to be concer- 

 dant, and of 2 pairs of dizygotic twins one of 

 which was discordant. Similar observations have 

 already been published by other authors. 



15.39. The Epidemiology of Spina Bifida Cystica. 



J. Lorber (Sheffield, Great Britain). 



In the Sheffield Children's Hospital a large 

 unit has been established for the care and study 

 of infants born with spina bifida cystica and over 

 100 new cases are seen each year. A detailed and 

 prospective family survey of over 500 unselected 

 families revealed a very much higher incidence 

 of multiple cases in sibships than hitherto re- 

 ported. In completing the family pedigree one 

 must not rely on a single interview or on the 

 evidence of non-medical persons not trained in 

 genetics. Frequently parents did not know the 

 cause of stillbirths or of neonatal deaths which 



occurred prior to or after the birth of the "index 

 case". Repeated questioning, enquiry from hos- 

 pitals and family doctors often disclosed such 

 additional cases. Further, a continuous follow- 

 up study of our patients allowed me to study 

 prospectively the condition of children born 

 after the index case. Finally, a detailed history is 

 taken of any congenital malformations which 

 occurred among cousins and in previous gene- 

 rations. Data are available now for thousands of 

 children. These indicate a strong, possibly 

 recessive genetic tendency. Among many inter- 

 esting features I have seven families in which 

 more than 2 siblings were affected. In these 

 families over 50 per cent of infants born after 

 the second affected child had either spina bifida 

 cystica, anencephaly or hydrocephalus. 



15.40. A Study of Mental Deficiency on Some 

 Causes. Yasuhiko Kobayashi, K. Kishi- 

 moto, M. Matsui, H. Tsuboi, Y. Shiraki, 

 and K. Nakai (Nagoya, Japan). 



We presume that mental deficiency is only a 

 "symptom name" due to its etiology. Mental 

 deficiency may be preferably considered to be a 

 collective name given to independent diseases 

 from the nosological point of view. 

 The following points may be considered: 



(1) Race 



(2) Sex 



(3) Polygenes (subcultural group) 



(4) One gene (pathological group-which is 

 less frequent in Japan than in Europe) 



(5) Chromosome aberration 



(6) Incompatibility of normal genes 



(7) Germinal injury 



(8) Foetal injury 



(9) Birth trauma 



(10) Injury in childhood 



Mental deficiency is not necessarily due to 

 only one cause. Mental deficiency may be in 

 consequence of the dynamic combination of 

 many causes. 



Here, we only make reference to consangui- 

 neous marriage, whose frequently in Japan is 

 10-20 times higher than in Europe, and in- 

 compatibility of blood types (ABO-type, MN- 

 type and Rh-type: Incompatibility of ABO- 

 blood type in Japan is possibly more frequent 

 than in Europe, because O-type in Japan is less 

 frequent than in Europe). 



For the same purpose we also studied electro- 

 encephalogram and amino acid in urine both on 

 patient and parents to find a few special forms 

 of amino aciduria, e.g. histidinuria, etc. We de- 



282 



