What Your Test Results Mean:

Carriers typically show no symptoms of neuronal ceroid lipofuscinosis; however, carriers are at an increased risk of having a child with neuronal ceroid lipofuscinosis. 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 for more detailed risk assessment.

Disease Explained:

TPP1-related neuronal ceroid lipofuscinosis is an inherited condition that impairs the cell’s ability to break down proteins and primarily affects the nervous system. In the late-infantile form, symptoms arise between the ages of 2 and 4, while onset of symptoms in the juvenile form occurs between the ages of 4 and 10. Symptoms typically begin with seizures, followed by progressive motor deterioration, developmental regression, and increasing intellectual disability. Affected individuals suffer rapid vision loss, becoming completely blind about 2-4 years after seizures begin. Treatment for neuronal ceroid lipofuscinosis is symptomatic.

How the Genetics Works:

TPP1-related neuronal ceroid lipofuscinosis is an autosomal recessive disorder caused by pathogenic variants in the TPP1 gene. In general, individuals have two copies of the TPP1 gene. Carriers of neuronal ceroid lipofuscinosis have a single variant in one copy of the TPP1 gene while individuals with neuronal ceroid lipofuscinosis 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%.