Section 15 — Human Genetics 



Orissa. The pedigree contains 182 people in 5 

 generations and has 5 sibships with at least one 

 affected member. Two of these sibships are 

 doubly related, the parents of each, though not 

 known to be related, being first cousins of the 

 parents of the other. All the 7 female and 4 male 

 deaf mutes recorded in this pedigree are the 

 progeny of non-consanguineous matings between 

 unaffected people. Three marriages of deaf mute 

 females to unaffected males produced six 

 unaffected sons. The evidence suggests that the 

 deaf mutism represented expression in the homo- 

 zygote of one of the autosomal recessive genes. 



15.50. Studies in the Aetiology of Congenital Deaf- 

 ness. George R. Fraser (London, Great 

 Britain). 



A series of 2355 children attending special 

 schools for the deaf in the British Isles was 

 studied. A clinical examination was performed 

 and a full family history obtained from the 

 parents. On the basis of data thus collected 

 together with a consideration of audiometric 

 patterns, the children were classified into aetio- 

 logical categories. 



In approximately 33 per cent of cases the 

 deafness was due to acquired disease in early 

 life, usually meningitis, and in 17 per cent it was 

 due to exogenous pre- and perinatal causes, the 

 most common of which were maternal rubella 

 and neonatal jaundice. 



Analysis of the data revealed that simple 

 Mendelian inheritance could account for the 

 deafness of the remaining 50 per cent. Recessive 

 types were most common but dominant and 

 sex-linked varieties were also present. Thus, in 

 12 per cent of this hereditary group the deafness 

 was inherited in a dominant and in 1 per cent in 

 a sex-linked manner. 



Three recessive syndromes were celarly 

 different iable clinically. Thus, deafness was 

 associated with goitre (Pendred's syndrome) 

 in 10 per cent of this hereditary group, with 

 retinitis pigmentosa (Usher's syndrome) in 

 2 per cent and with unique ECG abnormalities 

 in 1 per cent. In the dominant group, Waarden- 

 burg's syndrome (white forelock, heterochromia 

 of the irides, dystopia of the medial canthus of 

 the eyelid, congenital perceptive deafness) was 

 frequently seen. In many other families with 

 dominant deafness, lesser anomalies of pigmen- 

 tation were encountered. 



In 2 per cent of the entire group deafness was 

 associated with congenital malformations, in 

 some cases familial. While the Klippel Feil and 



Treacher Collins syndromes were the most 

 common in this group, some of these malfor- 

 mations were unique. 



15.51. Hereditary Hearing Impairment and Related 

 Anomalies. H. W. Kloepfer, Jeannette 

 Laguaite, and J. W. McLaurin (New 

 Orleans, U.S.A.). 



This is a preliminary progress report on 

 genetic, audiological and clinical data collected 

 over a period of five years from approximately 

 500 individuals who were selected from 2000 

 persons distributed in some 250 family units 

 in which deafness occurred at least in one parent 

 or offspring. Through a study of 4000 ancestors 

 of these families specific relationships between 

 family units and common ancestors can be 

 traced. Although all individuals have been placed 

 on 126 major pedigree charts, an IBM computer 

 program has been developed which will create 

 the information on a 9-generation pedigree 

 chart, find and evaluate each ancestor in terms 

 of association with family units in common, and 

 group family units according to the most 

 probable common genotype. 



At this stage of the study it would seem that 

 at least three independent autosomal recessive 

 genes (one later in life causing in addition retinitis 

 pigmentosa and cataract) account for the dear- 

 ness in most instances in a three-parish-area of 

 Louisiana in which all known cases of deafness 

 have been ascertained. However, hearing loss 

 was encountered in one kindred which is caused 

 by an autosomal dominant gene associated with 

 ear anomalies, brachial clefts, and ear pits. A 

 more detailed report will be given on this kindred. 



Supported by NIH Grant 22586. 



15.52. Deafness Associated with Split Hands and Feet 

 in Two Siblings. A New Syndrome? L. S. Wil- 

 dervanck (Groningen, the Netherlands). 



Two brothers, pupils of the Royal Institute of 

 the Deaf, Groningen, Holland, are suffering from 

 a perceptive deafness with a hearing loss of 60 to 

 80 db. An older brother and the parents, who are 

 not consanguineous, are hearing well. There is no 

 family history of deafness. Moreover the two 

 boys show split hands and feet, associated with 

 syndactyly. This anomaly is not known in the 

 family. Two sisters of the mother and a son of 

 one of them show a stiff thumb (radiographs 



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