Smoking as an aetiological factor in a pedigree with Leber’s hereditary optic neuropathy
- aDepartment of Ophthalmology, University of South Carolina School of Medicine, bDepartment of Ophthalmology, University of Vermont College of Medicine, cDepartments of Neurology and Ophthalmology, Harvard Medical School, Beth Israel Deaconess Medical Center
- Donald R Johns, MD, Harvard Institutes of Medicine, Room 858, 77 Ave Louis Pasteur, Boston, MA 02115, USA.
- Accepted 1 December 1998
Abstract
BACKGROUND/AIMS Leber’s hereditary optic neuropathy (LHON) is a mitochondrial DNA mediated disease which causes severe visual deficits. Although expressivity of the disease is 100%, penetrance is variable, and environmental factors may influence risk of becoming symptomatic. The causative relation between cigarette smoking and disease penetrance was examined.
METHODS The incidence of smoking in 65 age matched family members of one LHON pedigree was retrospectively obtained. Smoking in groups which expressed disease was compared with those which did not. Male subgroups were analysed separately in addition to combined sex groups.
RESULTS The association between smoking and disease penetrance was significant in all subgroups (p values from p=0.0009 to p=0.0001, 95% confidence intervals). Disease penetrance was higher in males than females. The association was weaker in the male group than combined sex groups (p values from p=0.0146 to p=0.0008, 95% confidence intervals), probably because of elimination of female asymptomatic non-smokers in the comparison groups. The association was strengthened in older age groups and in groups which smoked more heavily.
CONCLUSIONS Smoking is significantly associated with disease penetrance in this LHON pedigree. Degree of smoking and number of years smoked correlate with increased risk of developing symptoms.
