ALK-related neuroblastic tumor susceptibility is characterized by increased risk for neuroblastic tumors including neuroblastomas, ganglioneuroblastomas, and ganglioneuromas. Neuroblastomas are a more malignant tumor and ganglioneuromas a more benign tumor. Depending on the histologic findings, ganglioneuroblastomas can behave in a more aggressive fashion, like neuroblastomas, or in a benign fashion, like ganglioneuromas. The overall penetrance of a germline ALK pathogenic variant is approximately 50%, with the risk for neuroblastic tumor development highest in infancy and decreasing by late childhood.

Neoplasms located in the blood and blood-forming tissue (the bone marrow and lymphatic tissue).

A reduction in the number of circulating thrombocytes.

Prolongation of the time taken for a standardized skin cut of fixed depth and length to stop bleeding.

An abnormal susceptibility to bleeding, often referred to as a bleeding diathesis. A bleeding diathesis may be related to vascular, platelet and coagulation defects.

An impairment in the rate and degree to which platelets aggregate after the addition of an agonist that stimulates platelet clumping. Platelet aggregation is measured using aggregometer to measure the optical density of platelet-rich plasma, whereby platelet aggregation causes the plasma to become more transparent.