What causes Aarskog syndrome?
Last updated September 6, 2026.
Aarskog syndrome is caused by a change in a gene, most often the FGD1 gene on the X chromosome, and not by anything a parent did before or during pregnancy. FGD1 helps direct how bones, muscles, and connective tissue form during early development, so a change in it affects height, facial features, hands, and genital development. The condition follows an X-linked recessive pattern, which is why boys are affected more often and more noticeably, and why a mother who carries one altered copy may have only mild signs such as short fingers or a widow's peak. Many people who fit the clinical picture have no FGD1 change found on genetic testing, so other genes are likely involved and a negative test does not rule out the diagnosis. A clinical geneticist can confirm the diagnosis, order the right test, and explain what the result means for future pregnancies. Day to day, the practical work is steady growth monitoring plus regular dental, eye, and orthopedic checks.
What to do
- Ask for a genetics referral: A clinical geneticist or genetic counselor confirms the diagnosis and picks the right test.
- Map the family history: Write down height, hand shape, and facial features on the mother's side, since X-linked conditions travel through carrier females.
- Read a negative test carefully: No FGD1 change found does not undo a clinical diagnosis, so ask what the lab actually looked at.
- Track growth on a chart: Bring height and weight plots to each visit, because slow early growth with catch-up in the teen years is part of the pattern.
- Keep routine specialist checks: Dental, eye, and orthopedic reviews catch crowded teeth, vision changes, and joint problems early.
- Plan ahead for pregnancy: Ask about carrier testing and recurrence risk before a next pregnancy rather than after.
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