X-linked

In X-linked inheritance, the mutated gene is located on the 'x' chromosome, and is passed from a mother to her son.

Men have 'x-y' sex chromosomes, and they receive the 'x' chromosome from their mother, and the 'y' chromosome from their father. Women have 'x-x' sex chromosomes, and they receive one 'x' chromosome from their mother and the other from their father.

A woman with the defective 'x' chromosome will usually have no, or very mild, symptoms because the other, healthy 'x' chromosome counters the affect of the defective one. However, there is a 50% chance that she will pass on the defective gene to her son and that he will develop CMT.

If a woman with the defective 'x' chromosome only has daughters, CMT can skip a generation until one of her grandsons inherits the condition.