Mitochondrial DNA haplotype predicts deafness risk
- Univ. of Southern California, Los Angeles, CA (United States)
Since mitochondrial DNA (mtDNA) does not recombine in humans, once deleterious variation arises within a particular mtDNA clone it remains linked to that clonal type. An A to G mutation at mtDNA position 1555 confers matrilineal deafness among Asians and others. Two major mtDNA types (I and II) have been defined in Asians by D-loop sequencing. We have determined the D-loop sequence of 8 unrelated deaf Asians bearing the 1555G mutation, and find that 7 are of type II, whereas only one is of type I. Thus the frequency of the 1555G mutation is higher in type II mtDNA than type I (P = 0.035, binomial test), and persons with type II mtDNA are more likely to become deaf. Type II mtDNAs are rare in the Caucasian population, which may explain the rarity of this form of deafness in the United States. Negative Darwinian selection is expected to rapidly eliminate mtDNAs bearing severely deleterious mutations; but mildly deleterious mutations whose phenotype is expressed after reproduction should persist on the mtDNA background in which they arose. Thus determination of mtDNA clonal type has the potential to predict human risk for diseases that are the result of mildly deleterious mtDNA mutations which confer a post-reproductive phenotype. 4 refs., 1 fig.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 254418
- Journal Information:
- American Journal of Medical Genetics, Vol. 60, Issue 6; Other Information: PBD: 18 Dec 1995
- Country of Publication:
- United States
- Language:
- English
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