Observation on the epidemiology, genetics and pathogenesis of deafness in children and lower mammals

Abstract

Medical records of 1222 profoundly deaf people have been ascertained through the histories of students at the Clarke Schools for the Deaf, Northampton, Massachusetts. The data includes over 90% of all pupils at the school since its foundation in 1867.

About one-fifth of the children suffered from profound illness or trauma which clearly resulted in their hearing loss. These events have characteristics in common which make them recognizable in retrospect. Over-fourths of the deaf lacked a significant recorded history that could be clearly related to their deafness.

Genetic analyses of those cases of deafness without history of disease suggest that most are due to the action of a variety of genes acting in a simple mendelian manner. However, a significant number of cases result from factors such as undetected disease of complex genetic variation in thyroid function.

Among the cases of deafness resulting from dominant genes a clearly identifiable group has associated absence of normal body pigmentation. Depigmentation associated with deafness occurs in a variety of mammalian species. The development and pathology of the ear in this group will be discussed in some detail. Other genetic types of deafness reported in mammals will be related to the human codition.

Key Words:

• Deaf mutism
• Childhood deafness
• Segregation analysis
• Etiologic factors
• Genetic mechanisms
• Cochlear microphonic
• Histopathology