Creation Moment 12/16/2014 - 12S rRNA A1555G mutation

The 12S rRNA A1555G mutation in the mitochondrial haplogroup D5a is responsible for maternally inherited hypertension and hearing loss in two Chinese pedigrees

"We reported here clinical, genetic evaluations and molecular analysis of mitochondrial DNA (mtDNA) in two Han Chinese families carrying the known mitochondrial 12S rRNA A1555G mutation.

In contrast with the previous data that hearing loss as a sole phenotype was present in the maternal lineage of other families carrying the A1555G mutation, matrilineal relatives among these two Chinese families exhibited both hearing loss and hypertension.
Of 21 matrilineal relatives,
    9 subjects exhibited both hearing loss and hypertension,
    2 individuals suffered from only hypertension and
    1 member had only hearing loss.

The average age at onset of hypertension in the affected matrilineal relatives of these families was 60 and 46 years, respectively, whereas those of hearing loss in these two families were 33 and 55 years, respectively.

Molecular analysis of their mtDNA identified distinct sets of variants belonging to the Eastern Asian haplogroup D5a. In contrast, the A1555G mutation occurred among other mtDNA haplogroups D, B, R, F, G, Y, M and N, respectively. Our data further support that the A1555G mutation is necessary but by itself insufficient to produce the clinical phenotype. The other modifiers are responsible for the phenotypic variability of matrilineal relatives within and among these families carrying the A1555G mutation. Our investigation provides the first evidence that the 12S rRNA A1555G mutation leads to both of hearing loss and hypertension." EuropeanJournalOfHumanGenetics 
         

Hereditary hearing loss in Italian and Qatari population:

"Hereditary Hearing loss (HLL) is a common disorder accounting for at least 60% of prelingual deafness. GJB2 gene mutations, GJB6 deletion, and A1555G mitochondrial mutation play a major role worldwide and account for approximately 35% of Italian pathogenic alleles and almost no other common genes have been identified. Regarding the Qatari population, a molecular screening for these common genes/mutations on 126 Qatari patients clearly demonstrates that GJB2, GJB6 deletion and A1555G accounts for a minor proportion of NSHHL cases in this population." BioInternationalSchool

The mutation of A1555G illustrates the level of complexity of our genetic code. Apparently it is one of the building blocks relating to hearing. The detailed wiring of the human genome is almost beyond comprehension.....Mutations (losses of information) can begin to break down the machine of mankind....Or as Paul puts it For we know that the whole creation groaneth and travaileth in pain together until now. Romans 8:22