🧬 Gene Summary: GPC3
Associated with Simpson–Golabi–Behmel syndrome
What does the GPC3 gene do?
The GPC3 gene provides instructions to make a protein called glypican-3, which plays an important role in regulating growth and development before birth. It helps control how cells respond to growth signals, ensuring that organs and tissues develop at the right size and pace.
How can changes in the GPC3 gene cause hyperinsulinism?
When GPC3 does not work properly, growth-regulating signals can become overactive. In some children, this leads to excessive insulin release from the pancreas, even when blood sugar is low. As a result, affected infants may develop persistent or severe low blood sugar (hypoglycaemia), often beginning in the newborn period.
How common are changes in the GPC3 gene in hyperinsulinism?
Changes in GPC3 are a rare cause of hyperinsulinism. They are usually seen as part of a broader genetic condition rather than as an isolated finding.
How are changes in the GPC3 gene inherited?
Changes in GPC3 follow an X-linked inheritance pattern:
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Males with a disease-causing change are typically affected
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Females may be carriers and often have mild or no symptoms
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The gene change may be inherited from a carrier mother or arise new (de novo) in the child
đź’ˇ A genetic counsellor can help explain inheritance, testing options, and recurrence risks for your family.
What does a GPC3 change mean for my child?
Children with GPC3-related hyperinsulinism may:
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Have low blood sugar starting at or shortly after birth
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Have features of overgrowth, such as large size at birth
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Have additional congenital differences affecting other organs
Because GPC3-related hyperinsulinism occurs as part of a syndromic condition, care often involves multiple specialists.
Does GPC3 affect treatment?
Knowing that hyperinsulinism is caused by a GPC3 change helps doctors:
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Anticipate the course and severity of low blood sugar
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Decide on the most appropriate medical treatments
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Monitor for associated features of the syndrome
Management is usually medical rather than surgical and tailored to the child’s overall condition.
What about future children or family members?
Genetic testing can:
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Clarify the chance of hyperinsulinism or related features in future pregnancies
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Identify carrier family members
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Support informed family planning
Your healthcare team or genetic counsellor can guide you through these options.
Where can I learn more or get support?
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Speak with your child’s hyperinsulinism care team
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Meet with a genetic counsellor
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Connect with rare disease and hyperinsulinism support organisations