Humans have approximately 30.000 functional genes. We have two copies of every gene. One inherited from our biological mother and one from our biological father. A genetic disorder can be either autosomal recessive, autosomal dominant or X-linked or Y-linked.
The focus of the GeneMatch test
When a genetic disorder is autosomal recessive it means that the affected gene is located on a chromosome different from the sex chromosomes, and that the disorder only is expressed if both versions of that particular gene are mutated. With just one version of the genes mutated, one is said to be carrier of the mutation/disorder (but not affected). Expectedly, every person is carrier of mutations.
Being a carrier of a given mutation, there will be 50% risk that the mutation is passed on to children. This means that if both genetic parents are carrier of the same mutation, there will be a 50% risk that the child is carrier, 25% risk that the child will get both mutations and become sick, and 25% chance that the child will not get any of the mutations. Thus, the GeneMatch result “incompatibility is observed” means that with this donor you will have 25% risk of getting a sick child. SellmerDiers recommends you find a different donor in such a case.
When a genetic disorder is autosomal dominant, it means that the disorder will be expressed when only one of the two genes is affected. We do not focus on testing for autosomal dominant disorders since a such will be evident during the donor uptake process.
Disorders related to the sex chromosomes are called X-linked or Y-linked disorders. Since the Y-chromosome is very small compared to the X-chromosome, very few genetic disorders related to the sex chromosomes are Y-linked.
Females contain two X-chromosomes. Thus, a recessive X-linked disorder will not show in a female – only if both her X’es are affected by the same mutation. Males, however, containing both an X and a Y chromosome, will become sick if he carries an X-linked pathogenic mutation. This is because he does not have a healthy X to dominate the sick X. Therefore, for the same reason as for the autosomal dominant diseases, our donors are not genetically tested for X-linked disorders.
If a female is a carrier of an X-linked recessive disorder, her female offspring has a 50% risk of being a carrier of the same disorder (and 50% chance of not carrying). Her male offspring has the like risk of inheriting the disorder, however in contrast to the female offspring, the male offspring will become sick with the disorder if he has inherited the mutation.
When choosing our GeneMatch, 400+ genes most frequently related to autosomal recessive (and a few X-linked recessive) diseases will be matched to your chosen donor’s genetic profile.