Parental age - Birth order and congenital deafness

Abstract

The age of mother and father was investigated in 600 well documented cases of congenital deafness. The purposes of the investigation was to find out to what degree genetic mutations contribute to the incidence of congenital deafness.

Several variables have to be considered in view of the risks of various types associated with higher maternal age. Birth order has to be considered. The variables which have to be examined separately are as follows: High maternal age and high birth order; high maternal age and first child. High paternal age: older father and younger mother. The influence of these had to be analysed separately by excluding all the other effects (for example, the influence of high maternal age only, excluding the influence of high birth order, etc.).

The 600 cases were divided into the following aetiological groups: genetic, maternal rubella, neonatal anoxia, haemolytic disease of the newborn, and causes ‘unknown’, Each of these groups were analysed separately. The sex ratio in all these groups was examined (e.g. in the ‘unknown’ group there was a very highly significant number of males as compared with the general population, indicating the possibility of a sex-linked genetic type of deafness).

The overall results of the investigation are given in the paper.

Key Words:

• Genetic inheritance
• Genetic mutation
• Maternal rubella
• Neonatal anoxia
• Haemolytic disease of the newborn