If a patient has a mutation – or genetic change – in the ALK gene, the probability that a neuroblastic tumor will develop is presumed to be greater than 50%.
The risk of developing neuroblastic tumors is highest during infancy and decreases with age. With familial neuroblastomas, occur earlier (at the age of 9 months on average) than is the case with neuroblastomas when there is no increased familial incidence (at the age of 2-3 years on average).
In addition, there is a greater risk that multiple primary tumors will occur in familial neuroblastomas compared to the non-familial form. These multiple primary tumors may be bilateral adrenal gland tumors or multiple primary tumors outside of the adrenal glands that form in the cell cluster regions of the autonomic nervous system. The tumors may occur either concurrently or at differing times.