Genetic defect suggests high blood pressure may come from mom

A specific genetic defect in one Chinese family shows that high blood pressure was inherited from the female parent, researchers report in Circulation Research: Journal of the American Heart Association. The defect results from a point mutation — the substitution of a single DNA "base" for another during replication — in the genes of a tiny cellular organ called the mitochondria, which generates a cell's energy. When reproductive cells come together to form an embryo, the mitochondrial DNA from the mother cell is passed on to the offspring. Evidence has suggested a mother-child inheritance link for high blood pressure due to mitochondrial inheritance.

The Chinese-led group, which also included researchers from the Cincinnati Children's Hospital Medical Center and the Medical University of Vienna in Austria, provides clinical, genetic, molecular and biochemical evidence that a mitochondrial mutation designated tRNAIle 4263A>G is associated with inherited high blood pressure. The DNA substitution researchers discovered is an adenine-to-guanine switch at position 4263 on the mitochondrial genome (4263A>G).

Geneticists identified a large family from northern China in which 15 of 27 members who descended from the same female ancestor had blood pressures above 140/90 mmHg even after treatment. Only seven of 81 non-maternal relatives had high blood pressure.

Researchers compared the family members with 342 Chinese residents of the same northern area to confirm a maternal link. Analysis of the mitochondrial genome of the maternal relatives and other tests revealed the site of the hypertension-related mutation and showed that it impairs the mitochondrial respiration chain, which increases levels of a reactive oxygen species (i.e., free radicals).

The findings show that inherited mitochondrial dysfunction is involved in high blood pressure and may provide new insights into maternally transmitted hypertension, researchers said.

Source: American Heart Association