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Nonsyndromic deafness constitutes 75% of all hearing loss cases, and an estimated 100 genes are thought to be linked to this condition. About 80% are linked to autosomal recessive inheritance, 15% to autosomal dominant inheritance, 1-3% through the X chromosome, and 0.5-1% are associated with mitochondrial inheritance .
In X-linked hearing loss, the mother carries the recessive trait for hearing loss on the sex chromosome. She can pass on the trait to male and female children, but usually only male children are affected. There are some genetic syndromes, in which hearing loss is one of the known characteristics.
The most common type of congenital hearing loss in developed countries is DFNB1, also known as connexin 26 deafness or GJB2-related deafness. The most common dominant syndromic forms of hearing loss include Stickler syndrome and Waardenburg syndrome. The most common recessive syndromic forms of hearing loss are Pendred syndrome and Usher syndrome.
[7] [8] Autosomal recessive hearing loss is when both parents carry the recessive gene, and pass it on to their child. The autosomal dominant hearing loss is when an abnormal gene from one parent is able to cause hearing loss even though the matching gene from the other parent is normal. [9] This can lead to genetic syndromes, such as Down ...
[3] [14] Additionally, hearing loss is not as common as in type 2. [3] Rarely, cleft lip has been reported in this form of Waardenburg syndrome. [15] Type 4 can also be caused by a mutation in SOX10 (the same gene as in type 2E), in which it is known as type 4C; hearing loss is very common and severe in this type. [16]
DOOR (deafness, onychodystrophy, osteodystrophy, and mental retardation) syndrome is a genetic disease which is inherited in an autosomal recessive fashion. DOOR syndrome is characterized by mental retardation , sensorineural deafness , abnormal nails and phalanges of the hands and feet, and variable seizures .
Pendred syndrome; Other names: Goiter-deafness syndrome [1]: The normal cochlea has 2 & a half turns, but, in Pendred Syndrome, there is abnormal partitioning (the central bony core is reduced in size and complexity)and a reduced number of turns leading to a Mondini cochlea which has a basal turn and a dilated apical turn (1 & a half turns).
Corneal dystrophy-perceptive deafness syndrome; Other names: Congenital corneal dystrophy, progressive sensorineural deafness, Harboyan syndrome, CDPD (abbr.), Corneal dystrophy and sensorineural deafness. [1] This disorder is inherited in an autosomal recessive manner most of the time. Specialty: Medical genetics: Causes: Genetic mutation ...