Genetics of MLD

MLD is inherited as an autosomal recessive genetic disorder, which means both parents of the child must be “carriers” of the mutated gene to pass it along. It is believed that 1 in every 200 people is a carrier of MLD, which means there is a 1 in 40,000 chance that two carriers will have an affected child together.

If both parents are carriers:

- 25 % (1 in 4) child will have MLD

- 50 % (2 in 4) child will be carriers but not affected

- 25% (1 in 4) child will not be affected nor a carrier

If one parent is affected and one is free of MLD:

- 0% child will have the disorder- unaffected parent always gives normal gene

- 100% (4 in 4) child will be a carrier but unaffected

If one parent is a carrier and the other is free of MLD:

- 25% (1 in 4) child will be a carrier (but unaffected)

- 75% (3 in 4) child will not be affected nor a carrier