الفهرس 
INTRODUCTION AND RATIONALEOnly 14 pages are availabe for public view
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Abstract
Hearing loss cause speech, language, and cognitive development impairment which can be prevented by early hearing assessment . Nearly half of children having permanent hearing impairment is due to genetic cause ,30% of the genetic causes of hearing loss is syndromic and 70% of the cases is non-syndromic hearing loss . Approximately 70-80% is autosomal recessive,15-20% autosomal dominant and 2-3% are x-linked or mitochondrial.
The effect of consanguinity on hereditary deafness has been well studied and documented. Many authors by using statistics principles and causes of deafness believe that` consanguineous marriage will increase the chance of deafness by autosomal recessive genes. Some authors suggest such marriage should be avoided as they make double the risk of infants with birth defects such as mental retardation, deafness and blindness when compared with an ”unrelated” marriage. Many authors have suggested that approximately one half of sensory neural hearing loss in children can be attributed to hereditary causes
The current study was done in Menoufia university hospital, on a group included 1122 subjects , with age range 0.5 – 12 years . This study is comprised of two age and sex matched subgroups; Hearing Loss group and Normal Hearing group. The children with hearing loss were due to genetic origin only while other confounding factors; any child with history of jaundice, neonatal sepsis or any other disorder that may induce SNHL were not included in our study.
Among the study group no consanguinity was in 194 (37%) ,first degree consanguinity was in 201 (38.3%) second degree consanguinity was in 130 (24.8%) while in control group no consanguinity was in 360 (60.3%),first degree consanguinity was in 178 (29.8%) second degree consanguinity was in 59 (9.9%) .
In our study percent of consanguinity in study group is 58.3% and in control group is 41.7%.Percent of no consanguinity in study group is 35% and in control group is 65%.