Homoplasmy of the G7444A mtDNA and heterozygosity of the GJB2 c.35delG mutations in a family with hearing loss.
OBJECTIVE
Mitochondrial mutations have been shown to be responsible for syndromic as well as non-syndromic hearing loss. The G7444A mitochondrial DNA mutation affects COI/the precursor of tRNA(Ser(UCN)), encoding the first subunit of cytochrome oxidase. Here we report on the first Greek family with the G7444A mitochondrial DNA mutation.


METHODS
Clinical, cytogenetic, and molecular methods were employed in this study.


RESULTS
We describe the high variability of phenotypes among three family members harboring the G7444A mutation and also the frequent GJB2 c.35delG mutation of the nuclear genome in heterozygosity. Their phenotypes ranged from normal hearing to deafness, while the proband presented with several other symptoms.


CONCLUSIONS
The G7444A mitochondrial DNA mutation has been reported in only a few cases worldwide, alone or in cosegregation with other mitochondrial DNA mutations, but to our knowledge, never before in coexistence with the GJB2 c.35delG mutation.
Department of Genetics, Institute of Child Health, Aghia Sophia Children's Hospital, Athens, Greece. hkokotas@yahoo.gr
Haris
H
Kokotas
Maria
M
Grigoriadou
Li
L
Yang
Marianne
M
Lodahl
Nanna Dahl
ND
Rendtorff
Yolanda
Y
Gyftodimou
George S
GS
Korres
Elisabeth
E
Ferekidou
Dimitrios
D
Kandiloros
Stavros
S
Korres
Lisbeth
L
Tranebjærg
Min-Xin
MX
Guan
Michael B
MB
Petersen
D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D050259:Genes, Mitochondrial / Q000235:genetics*; D006580:Genetic Carrier Screening; D020022:Genetic Predisposition to Disease; D006115:Greece; D034381:Hearing Loss / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D008297:Male; D010375:Pedigree; D017354:Point Mutation; D012343:RNA, Transfer / Q000235:genetics; D018570:Risk Assessment
D017630:Connexins; D004272:DNA, Mitochondrial; C000607042:GJB2 protein, human; D000072259:Connexin 26; D012343:RNA, Transfer