Deafness in children: The most common cause for congenital deafness is consanguineous marriages

By Syed Akbar
Hyderabad: Children born of close relation wedlock are known to
suffer from a variety of genetic disorders
and a fresh study by a team of city doctors and geneticists shows that
they are highly prone to congenital deafness
too.
A joint study by the Institute of Genetics and Hospital for Genetic
Diseases and the ENT department of Osmania
General Hospital reveals that children born out of consanguineous
marriages are two times more susceptible to
congenital deafness than ordinary children. The study was conducted in
Government ENT Hospital and in various
schools for the deaf in and around Hyderabad. The subjects ranged from
neonates to children up to 14 years of age.
Dr PP Reddy of the Institute of Genetics told this correspondent that
among various causes for deafness, consanguinity is an established high
risk etiological factor.
"The results showed that 41.73 per cent of the cases were the products of
consanguineous matings and 58.27 per cent
were born to non-consanguineous parents. Further analysis revealed a high
rate of consanguinity (44.53 per cent) in
children with non syndromic deafness. The percentage of consanguineous
marriages in Andhra Pradesh is 22.36 but
the rate of deafness in children born out of such wedlock is 41.73 per
cent," he pointed out.
He said hearing impairment had debilitating effects on children as it
could  retard individual's language acquisition
skills and impair the overall development. It is rapidly increasing
sensory deficit among human beings and accounts
for one third of the entire disease burden in the world.
The world-wide prevalence of profound, congenital deafness is 11 per 10,000
children, and is attributable to genetic causes in at least 50 per cent of
the cases. The survey indicated that one out of
every 1000 children born in India showed profound hearing loss.
Dr Reddy said the siblings of consanguineous marriages have a
significantly higher incidence of autosomal recessive
diseases including hearing impairment. Marriages within the family
increase the risk of hearing impairment and other
diseases.
"The development of cochlea and hair cells is dependent on a genetic
pathway called Planar Cell Polarity pathway.
This pathway is involved in the formation of the polarised structure of
the auditory sensory organ and
regulates the embryonic development. Genetic aberrations caused due to
consanguinity disturb the pathway leading
to congenital hearing loss," he said.