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The load of genetic and partially genetic disease in man. IV. Severe visual handicaps and profound childhood deafness in Hungarian school-age children
Authors:A Czeizel  K Skirpeczky  E Mester  K Sankaranarayanan  
Institution:

a Department of Human Genetics and Teratology, National Institute of Hygiene, WHO Collaborating Centre for the Community Control of Hereditary Disease, Budapest, Hungary

b MGC, Department of Radiation Genetics and Chemical Mutagenesis, Sylvius Laboratories, State University of Leiden, Leiden, Netherlands

Abstract:In Hungary, the school-age prevalences of severe visual handicaps and of profound childhood deafness have been estimated to be about 6/104 and 10/104, respectively. Most of these conditions have onset at birth or in early childhood and are aetiologically heterogeneous.

Severe visual handicaps are grouped under 11 aetiological categories, their relative contributions to the prevalence being: perinatal damage syndrome (20%; half of this is due to retinopathy of premature infants), cataracts (15%), choroidoretinal degenerations (15%), congenital abnormalities of the eye (15%), syndromes (10%), high myopia ± retinal detachment (7%), postnatal causes (5%), nystagmus (5%), optic atrophy (4%), bilateral retinoblastoma (2%) and prenatal causes (2%). Overall, Mendelian conditions (included under many of the above) account for about 50% with relatively more autosomal dominant than autosomal recessive and sex-linked entities, and acquired causes account for about 40% of the cases studied. No actiology could be assigned in 10% of the cases.

For profound childhood deafness, the rank order of the aetiological categories is: autosomal recessive entities (34%), postnatal causes (22%), perinatal causes (19%), autosomal dominant entities (17%), prenatal causes (5%) and unknown causes (3%).

Severe childhood visual handicaps are responsible for about 60 years of loss of life per 104 live births and about 400 years of impaired life per 104 live births. Genetic causes account for one-quarter of lost life years and three-quarters of impaired life years. The comparable estimates for profound childhood deafness are: about 240 years of life loss per 104 live births (again, about one-quarter due to genetic causes) and about 640 years of impaired life per 104 live births (about one-half due to genetic causes). In all these calculations, it has been assumed that the average life expectancy at birth for an individual in the population is 70 years.

Keywords:Visual handicap  Deafness  Hungary
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