Is Alternating Hemiplegia Of Childhood hereditary?

Alternating Hemiplegia of Childhood is a rare genetic disorder, but it is rarely inherited from parents; in the vast majority of cases, it is caused by a de novo (spontaneous) mutation. Because these mutations occur randomly at the time of conception, the condition is considered genetic but usually not hereditary in the traditional sense, meaning the risk of recurrence for siblings is extremely low.

Is Alternating Hemiplegia of Childhood an inherited condition?

While Alternating Hemiplegia of Childhood is a genetic disorder, most affected individuals do not have a family history of the disease. The condition is primarily caused by a mutation in the ATP1A3 gene. Because this mutation typically occurs de novo, the parents of a child with Alternating Hemiplegia of Childhood usually do not carry the gene mutation themselves, making the likelihood of having another affected child very low, generally estimated at less than 1%.

What is the role of genetic testing in Alternating Hemiplegia of Childhood?

Genetic testing is the gold standard for confirming a diagnosis of Alternating Hemiplegia of Childhood. Clinical molecular testing, such as targeted gene sequencing or panel testing for the ATP1A3 gene, can identify the specific pathogenic variant. Genetic counseling is highly recommended for all families navigating this diagnosis to understand the following:

• The distinction between a de novo mutation and inherited genetic conditions.


• The current capabilities and limitations of molecular diagnostic testing.


• Options for family planning, including reproductive technologies.


• The interpretation of test results for siblings or extended family members.

How common are de novo mutations in this condition?

Research indicates that over 90% of Alternating Hemiplegia of Childhood cases result from a sporadic de novo mutation. In the rare instances where a parent does carry the mutation, they may exhibit mosaicism (where only some cells carry the mutation), which can lead to milder symptoms or an asymptomatic state. For the 72 members of the Alternating Hemiplegia of Childhood community on DiseaseMaps.org, understanding the de novo nature of the gene mutation often provides clarity and reduces parental guilt regarding the cause of the disorder.

Next steps

• Consult with a board-certified clinical geneticist to discuss ATP1A3 testing.


• Connect with the Alternating Hemiplegia of Childhood community at DiseaseMaps.org to share experiences and find support.


• Request a referral to a genetic counselor to discuss recurrence risks specific to your family's genetic profile.

Medical disclaimer: This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment by a qualified healthcare provider.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Alternating Hemiplegia of Childhood


• OMIM (Online Mendelian Inheritance in Man): #104290 (ATP1A3-related disorders)


• Orphanet: Rare Disease Database (ORPHA:392)


• Alternating Hemiplegia of Childhood Foundation (AHCF)