Section 15 — Human Genetics 



with a varying expressivity and weak specificity 

 (polypheny). 



15.47. An Apparently Sex-linked Heredo-degenerative 

 Disease of the Central Nervous System 

 combined with Leber's Optic Atrophy. 



L. N. Went and G. W. Bruyn (Leyden, 

 the Netherlands). 



The index case of the family to be reported here 

 was suffering since his 7th year from a here- 

 dodegenerative disorder for which he has been 

 admitted 6 times and which has been diagnosed 

 on several occasions as spastic paraplegia. 

 In addition he experienced on acute bilateral 

 decrease of vision when 36 years old; pale discs, 

 central scotomas and a vision of 1/60 ODS were 

 found. 



His family could be studied over 7 generations 

 and revealed in addition 5 persons with both 

 abnormalities, 6 with optic atrophy only and 

 6 with the neurological disorder only. All 

 patients were males, while their clinical picture 

 was almost identical. Clinically it seems likely 

 that a basal ganglia disease is responsible for the 

 neurological findings. The only female family 

 member affected (who had an affected brother 

 and an affected son) was clinically very different 

 from the others and had actually been diagnosed 

 as a case multiple sclerosis. 



The distribution of the affected patients over 

 the family is such that it seems justified to 

 conclude that only one gene, most probably on 

 the X-chromosome, is responsible for both the 

 neurological and ophthalmological abnormali- 

 ties. 



Chromosomal and linkage studies and ex- 

 tensive biochemical investigations have been 

 undertaken or are under way and will be reported 

 upon. Our findings will be published in detail 

 elsewhere. 



which some cases belong to Bardet-Biedl 

 syndrome, congenital tapeto-retinal amaurosis 

 of Leber, retinitis punctata albescens and fundus 

 albipunctatus cum hemeralopia. About 90 per 

 cent of those cases are transmitted by the 

 recessive mode of inheritance, and 9 per cent are 

 dominant. One family only presents a recessive 

 sex-linked transmission of retinitis pigmentosa. 

 In this family, the female heterozygotes show 

 the tapeto-retinal reflex which was never ob- 

 served before in Switzerland. If we keep out the 

 cases of fundus albipunctatus, because of its 

 special clinical character, and the cases of 

 Bardet-Biedl syndrome, we find in 5 cantons 

 101 living persons suffering from recessive 

 pigmentary degeneration. This fact allows us to 

 estimate the frequency of this affection at 1 :7000, 

 the gene frequency at 1/84 and the frequency of 

 the heterozygotes at about 1/42. 10 per cent of 

 these 101 cases are issued from unions between 

 first cousins. 



Among the hereditary affections associated 

 with tapeto-retinal degeneration, congenital 

 deafness is known as the most frequent; indeed 

 we discovered this type of association in about 

 13 per cent of our material, while psychiatric 

 disorders as oligophrenia and psychoses do not 

 seem to be more frequent in the affected people 

 than in the general population. The Bardet- 

 Biedl syndrome was observed in four patients out 

 of a population of 700.000 inhabitants. 



The great diversity of clinical forms of the 

 tapetoretinal degeneration raises the problem 

 of heterophenia of tapeto-retinal degenerations. 

 Indeed, the study of an isolate in the canton of 

 Valais allowed us to demonstrate a phenotypical 

 alternation between different types of pigmentary 

 degeneration within several branches of a large 

 family issued from the same ancestor. This 

 pedigree comprises 7 cases of peripheral tapeto- 

 retinal degeneration in 2 sibships, 5 cases of 

 macular degeneration in 5 sibships and 3 cases 

 of fundus albipunctatus cum hemeralopia in 2 

 sibships. 



15.48. (D.). Genetic and Epidemiological Investiga- 

 tions on Pigmentary Degeneration of the Retina 

 in Switzerland. F. Ammann, D. Klein and 

 A. Franceschetti (Geneva, Switzerland). 



Since 1959 we are dealing with a genetic and 

 epidemiological investigation on all types of 

 pigmentary degeneration of the retina in 

 Switzerland. We relate here the results obtained 

 until now in about 10 of 22 cantons. 



Our material is composed of the following 

 clinical types of pigmentary degeneration: 

 typical and atypical retinitis pigmentosa out of 



15.49. A Pedigree of Reccessive Deaf Mutism from 

 Orissa, India. K. R. Dronamraju (Orissa, 

 India). 



A pedigree of Bengali Kayastha settlers in 

 Orissa, India was investigated for the inheritance 

 of hereditary deaf mutism. This is a small 

 endogamous community in which consangui- 

 neous marriages are scrupulously avoided. The 

 propositus was a female congenital deaf mute 

 aged 17 years and was a student at the School 

 for the Deaf and Dumb in Bhubaneswar, 



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