[Analysis of clinical phenotype in 42 nuclear pedigrees carrying mitochondrial DNA A3243G mutation]

A3243G mutation in mitochondrial DNA is the most common pathogenic point mutation causing a variety of phenotypes. The clinical phenotype and the relationship between the clinical phenotype and the ratio of A3243G mutation were studied in the members from nuclear families carrying A3243G mutation.

A total of 42 families carrying A3243G mutation were recruited and their clinical symptoms, laboratory results and the ratio of A3243G analyzed.

(1) In probands, myopathy, seizure, hirsutism, headache, cognitive impairment, weight loss and short stature were the most common clinical features. They tended to occur simultaneously. Lactic acid, pyruvate and MRI were abnormal in most probands; (2) most carriers had a normal phenotype. Myopathy, weight loss and short stature were their most common clinical features; (3) the ratio of A3243G mutation in urine was higher than that in blood in probands (t = -15.06, P < 0.001). And the ratio of A3243G mutation in urine was higher than that in blood in their mothers (z = -6.241, P < 0.001); (4) the ratio of A3243G mutation in probands was 2-fold higher than that in their mothers in both blood and urine.

The phenotype of patients carrying A3243G mutation is varied. The clinical symptoms and laboratory results of probands are worse than those of mothers. It is probably due to a higher mutation ratio of m.3243A>G in their tissues.