Autosomal recessive inheritance

Autosomal recessive inheritance d.doran@muscul… Wed, 05/19/2021 - 17:03

‘Autosomal’ means the mutation is in a gene on the non-sex chromosomes, so children of either sex can inherit the condition. ‘Recessive’ means both copies of that gene have to be mutated for someone to have the condition. If only one copy of the gene is mutated, that person is a carrier and will have no symptoms.

If mother and father are both carriers, (see first diagram), there is a:

  •  25 percent chance that each child will be unaffected
  •  50 percent chance that each child will be a carrier
  •  25 percent chance that each child will have the condition.
Image
This diagram shows what would happen if two carrier parents of an Autosomal Recessive condition had children. Of the 4 children they have; 1 would be unaffected, 1 would be affected, and 2 others would both be carriers.

Diagram 1

Parents with autosomal recessive conditions will pass on one copy of the mutated gene to their children (see second diagram). It is very unlikely their children will be affected (unless the other parent is a blood relative).

Image
This diagram shows what would happen if an affected parent with a recessive condition and a non-carrier parent have children. All 4 of their children will be carriers.

Diagram 2

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