Over the last decade, a number of distinct mutations in the mtDNA (mitochondrial DNA) have been found to be associated with both syndromic and non-syndromic forms of hearing impairment. Their real incidence as a cause of deafness is poorly understood and generally underestimated. Among the known mtDNA mutations, the A1555G mutation in the 12S gene has been identified to be one of the most commo...

EDITOR—Around 1 in 1000 children is born or presents in early childhood with a severe hearing impairment. 2 In developed countries, approximately 50% of these cases are attributed to genetic causes and the majority are non-syndromic with an autosomal recessive mode of transmission. Childhood onset nonsyndromic sensorineural hearing loss (NSSNHL) is almost exclusively monogenic. This has facilit...

H earing impairment is a common condition responsible for communication disorders affecting one in 1000 newborns. 2 A national poll by the China Association of the Handicapped in 1987 showed that 20.57 million people in the country were affected by auditory or speech disorders, accounting for 34% of the 60 million disabled or 1.58% of the total Chinese population (1.3 billion) (www.cdpf.org.cn)...

BACKGROUND Hereditary forms of hearing loss are classified as syndromic, when deafness is associated with other clinical features, or non-syndromic, when deafness occurs without other clinical features. Many types of syndromic deafness have been described, some of which have been mapped to specific chromosomal regions. METHODS Here we describe a family with progressive sensorineural hearing l...

F amilial hypertrophic cardiomyopathy (FHC) is typically characterised by left ventricular hypertrophy, diastolic dysfunction, and hypercontractility, and is often associated with disabling symptoms, arrhythmias, and sudden death. FHC shows both non-allelic and allelic genetic heterogeneity, and results from any one of more than 100 mutations in genes encoding sarcomeric proteins. Identified ge...

OBJECTIVES Non-syndromic sensorineural hearing loss (NSHL) is a common disorder affecting approximately 1 in 500 newborns. This type of hearing loss is extremely heterogeneous and includes over 100 loci. Mutations in the GJB2 gene have been implicated in about half of autosomal recessive non-syndromic hearing loss (ARNSHL) cases, making this the most common cause of ARNSHL. For the latter form ...

BACKGROUND The estimated prevalence of Sensory Neural Hearing Loss (SNHL) in patients less than 18 years of age is 6 per 1000. Roughly 50% of cases of congenital SNHL can be linked to a genetic cause, with approximately 30% being syndromic and the remaining 70% being non-syndromic. The term "syndromic" implies the presence of other distinctive clinical features in addition to hearing loss. The ...