During the past decade, there have been many descriptions of patients with
neurological disorders due to mitochondrial DNA (mtDNA) mutations, but the
extent and spectrum of mtDNA disease in the general population have not yet
been defined Adults with suspected mtDNA disease in the North East of Engl
and were referred to a single neurology center for investigation over the 1
0-year period from 1990 to 1999 inclusive. We defined the genetic defect in
these individuals. For the midyear period of 1997, we calculated the minim
um point prevalence of mtDNA disease in the adults of working age (>16-<60
years old for female subjects and <65 years old for male subjects) and the
minimum prevalence of adults and children (<60 years for female subjects, <
65 years for male subjects) at risk of developing mtDNA disease. mtDNA defe
cts caused disease in 6.57 per 100,000 individuals in the adult population
of working age, and 7.59 per 100,000 unaffected adults and children were at
risk of developing mtDNA disease. overall, 12.48 per 100,000 individuals i
n the adult and child population either had mtDNA disease or were at risk o
f developing mtDNA disease. These results reflect the minimum prevalence of
mtDNA disease and pathogenic mtDNA mutations and demonstrate that pathogen
ic mtDNA mutations are a common cause of chronic morbidity. These findings
have resource implications, particularly for supportive care and genetic co
unseling.