Which are the causes of Hajdu-Cheney Syndrome?

Hajdu-Cheney syndrome is a rare connective tissue disorder caused by specific mutations in the NOTCH2 gene, which lead to an overactive signaling pathway that disrupts bone remodeling. Because this is a genetic condition, it is not caused by environmental factors, lifestyle, or autoimmune triggers, but rather by an inherited or spontaneous alteration in DNA.

What causes Hajdu-Cheney syndrome at the genetic level?

The primary cause of Hajdu-Cheney syndrome is a mutation in the NOTCH2 gene. This gene provides instructions for creating a protein that acts like a cellular "switch," helping to regulate bone development and maintenance. In individuals with Hajdu-Cheney syndrome, these mutations result in a protein that remains "stuck" in the "on" position. Think of it like a thermostat that is jammed, causing the body to break down bone tissue faster than it can be replaced, which leads to the characteristic bone loss and skeletal abnormalities seen in the syndrome.

Is Hajdu-Cheney syndrome inherited?

Hajdu-Cheney syndrome is typically inherited in an autosomal dominant pattern. This means that only one copy of the mutated gene from one parent is required to manifest the condition. However, many documented cases of Hajdu-Cheney syndrome occur as a "de novo" mutation, meaning the genetic change happens spontaneously in the individual without a family history of the disease.

Are there environmental triggers for this condition?

There is no evidence that environmental factors, infections, or toxins cause Hajdu-Cheney syndrome. Because the etiology is strictly genetic, the disease process is determined at the moment of conception. Research into the pathophysiology of Hajdu-Cheney syndrome is currently focused on:

• Developing therapies that target the overactive NOTCH2 signaling pathway.


• Understanding why specific bones (like the acro-osteolysis of the fingertips) are more severely affected than others.


• Identifying additional genetic modifiers that might explain why symptom severity varies between patients.

Next steps

• Consult with a clinical geneticist to confirm a diagnosis through molecular genetic testing.


• Speak with an endocrinologist or metabolic bone specialist to manage bone density and skeletal health.


• Connect with the 5 members of our DiseaseMaps.org community who are living with this condition to share experiences and coping strategies.

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

References

• NIH Genetic and Rare Diseases Information Center (GARD): Hajdu-Cheney Syndrome.


• Online Mendelian Inheritance in Man (OMIM): #102500 - Hajdu-Cheney Syndrome.


• Orphanet: ORPHA2097 - Hajdu-Cheney Syndrome.