Dubowitz syndrome (DS) is a rare multiple congenital syndrome characterized primarly by growth retardation, microcephaly, distinctive facial dysmorphism, cutaneous eczema, a mild to severe intellectual deficit and genital abnormalities.

RUNX1 familial platelet disorder with associated myeloid malignancies (RUNX1-FPDMM) is characterized by prolonged bleeding and/or easy bruising and an increased risk of developing a hematologic malignancy. RUNX1-FPDMM is characterized by thrombocytopenia with normal platelet size; bleeding is often greater than expected due to qualitative platelet dysfunction. Myeloid malignancies are the most common, including acute myelogenous leukemia (and myelodysplastic syndrome. T- and B-cell acute lymphoblastic leukemias and lymphomas have also been reported, as well as skin manifestations (e.g., eczema, psoriasis).

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Hereditary paraganglioma-pheochromocytoma (PGL/PCC) syndromes are characterized by paragangliomas (tumors that arise from neuroendocrine tissues distributed along the paravertebral axis from the base of the skull to the pelvis) and pheochromocytomas (paragangliomas that are confined to the adrenal medulla). Sympathetic paragangliomas cause catecholamine excess; parasympathetic paragangliomas are most often nonsecretory. Extra-adrenal parasympathetic paragangliomas are located predominantly in the skull base and neck (referred to as head and neck PGL [HNPGL]) and sometimes in the upper mediastinum; approximately 95% of such tumors are nonsecretory. In contrast, sympathetic extra-adrenal paragangliomas are generally confined to the lower mediastinum, abdomen, and pelvis, and are typically secretory. Pheochromocytomas, which arise from the adrenal medulla, typically lead to catecholamine excess. Symptoms of PGL/PCC result from either mass effects or catecholamine hypersecretion (e.g., sustained or paroxysmal elevations in blood pressure, headache, episodic profuse sweating, forceful palpitations, pallor, and apprehension or anxiety). The risk for developing metastatic disease is greater for extra-adrenal sympathetic paragangliomas than for pheochromocytomas.

In addition, neuroblastoma tumors can release hormones that may cause other signs and symptoms such as high blood pressure, rapid heartbeat, flushing of the skin, and sweating. In rare instances, individuals with neuroblastoma may develop opsoclonus myoclonus syndrome, which causes rapid eye movements and jerky muscle motions. This condition occurs when the immune system malfunctions and attacks nerve tissue.\n\nIndividuals with neuroblastoma may develop general signs and symptoms such as irritability, fever, tiredness (fatigue), pain, loss of appetite, weight loss, or diarrhea. More specific signs and symptoms depend on the location of the tumor and where it has spread. A tumor in the abdomen can cause abdominal swelling. A tumor in the chest may lead to difficulty breathing. A tumor in the neck can cause nerve damage known as Horner syndrome, which leads to drooping eyelids, small pupils, decreased sweating, and red skin. Tumor metastasis to the bone can cause bone pain, bruises, pale skin, or dark circles around the eyes. Tumors in the backbone can press on the spinal cord and cause weakness, numbness, or paralysis in the arms or legs. A rash of bluish or purplish bumps that look like blueberries indicates that the neuroblastoma has spread to the skin.\n\nNeuroblastoma occurs most often in children before age 5 and rarely occurs in adults.\n\nNeuroblastoma is a type of cancer that most often affects children. Neuroblastoma occurs when immature nerve cells called neuroblasts become abnormal and multiply uncontrollably to form a tumor. Most commonly, the tumor originates in the nerve tissue of the adrenal gland located above each kidney. Other common sites for tumors to form include the nerve tissue in the abdomen, chest, neck, or pelvis. Neuroblastoma can spread (metastasize) to other parts of the body such as the bones, liver, or skin.

A variant of neurofibromatosis type 1 characterized by the combination of features of neurofibromatosis type 1, such as café-au-lait spots, iris Lisch nodules, axillary and inguinal freckling, optic nerve glioma and multiple neurofibromas; and Noonan syndrome, with features such as short stature, typical facial features, congenital heart defects and unusual pectus deformity.

Lynch syndrome is characterized by an increased risk for colorectal cancer (CRC) and cancers of the endometrium, ovary, stomach, small bowel, urinary tract, biliary tract, brain (usually glioblastoma), skin (sebaceous adenomas, sebaceous carcinomas, and keratoacanthomas), pancreas, and prostate. Cancer risks and age of onset vary depending on the associated gene. Several other cancer types have been reported to occur in individuals with Lynch syndrome (e.g., breast, sarcomas, adrenocortical carcinoma). However, the data are not sufficient to demonstrate that the risk of developing these cancers is increased in individuals with Lynch syndrome.

Congenital central hypoventilation syndrome (CCHS) represents the extreme manifestation of autonomic nervous system dysregulation (ANSD) with the hallmark of disordered respiratory control. The age of initial recognition of CCHS ranges from neonatal onset (i.e., in the first 30 days of life) to (less commonly) later onset (from 1 month to adulthood). Neonatal-onset CCHS is characterized by apparent hypoventilation with monotonous respiratory rates and shallow breathing either during sleep only or while awake as well as asleep; ANSD including decreased heart rate beat-to-beat variability and sinus pauses; altered temperature regulation; and altered pupillary response to light. Some children have altered development of neural crest-derived structures (i.e., Hirschsprung disease, altered esophageal motility/dysphagia, and severe constipation even in the absence of Hirschsprung disease) and/or tumors of neural crest origin (neuroblastoma, ganglioneuroma, and ganglioneuroblastoma). Neurocognitive delay is variable, and possibly influenced by cyanotic breath holding, prolonged sinus pauses, need for 24-hour/day artificial ventilation, and seizures. Later-onset CCHS is characterized by alveolar hypoventilation during sleep and attenuated manifestations of ANSD.

Megalencephaly-polydactyly syndrome (MPAPA) is an autosomal dominant disorder characterized by megalencephaly, ventriculomegaly, postaxial polydactyly, and, notably, neuroblastoma during infancy (summary by Nishio et al., 2023).