What Your Test Results Mean:

Carriers typically show no symptoms of Segawa syndrome; however, carriers are at an increased risk of having a child with Segawa syndrome. 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:

Segawa syndrome is an inherited condition characterized by muscle rigidity, unusual limb positioning, a lack of coordination when walking or running, unusually slow movement, tremors, and an inability to hold the body upright and balanced. These symptoms range from mild to severe depending on the case. The symptoms of the disorder are caused by a deficiency of the enzyme tyrosine hydroxylase, preventing production of the neurotransmitter dopamine. Milder cases can be very successfully treated with medications. If symptoms have gone untreated for a while, some symptoms such as uneven gait and motor and speech difficulties may not reverse with medication but improve with physical, occupational, and/or speech therapy.

How the Genetics Works:

Segawa syndrome is an autosomal recessive disorder caused by pathogenic variants in the TH gene. In general, individuals have two copies of the TH gene. Carriers of Segawa syndrome have a single variant in one copy of the TH gene while individuals with Segawa syndrome 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%.