What Your Test Results Mean:

Carriers typically show no symptoms of AMRS; however, carriers are at an increased risk of having a child with AMRS. Risk for the current or future pregnancies is dependent on your partner’s carrier status. Carrier testing of your partner is recommended in addition to consultation with a genetic counselor.

Disease Explained:

AMRS is an inherited condition that is caused is caused by abnormalities in a glycan transporter. Carbohydrate chains (glycans) are normally attached to the outside of the cell membrane so that cells can communicate with each other
and tissues can be properly developed and maintained. These carbohydrate structures cannot be moved to the cell membrane without the transporter, leading to serious health problems for individuals with AMRS. The major symptoms of AMRS are described in its name: affected individuals suffer from arthrogryopsis (immobility of the joints due to muscle fibrosis), mental retardation, and seizures. In addition, individuals with AMRS have usually small head size, poor muscle tone, and autism. There is no cure for AMRS.

How the Genetics Works:

AMRS is an autosomal recessive disorder that can be explained by pathogenic variants in the SLC35A3 gene. In general, individuals have two copies of the SLC35A3 gene. Carriers of AMRS have a single variant in one copy of the SLC35A3 gene while individuals with AMRS have variants in both copies of their genes, one inherited from each parent. Risk for two carriers to have a child with the disorder is 25%.