MedGen

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. [from SNOMEDCT_US]

Spinal neurofibromatosis is an autosomal dominant disorder characterized by a high load of spinal tumors. These tumors may be asymptomatic or result in neurologic symptoms, including back pain, difficulty walking, and paresthesias. Spinal NF is considered to be a subtype of neurofibromatosis type I (NF1; 162200), which is an allelic disorder. Patients with spinal NF may or may not have the classic cutaneous cafe-au-lait pigmentary macules or ocular Lisch nodules typically observed in patients with classic NF1. Patients with spinal NF should be followed closely for spinal sequelae (summary by Burkitt Wright et al., 2013). [from OMIM]

Juvenile myelomonocytic leukemia is an aggressive pediatric myelodysplastic syndrome (MDS)/myeloproliferative disorder (MPD) characterized by malignant transformation in the hematopoietic stem cell compartment with proliferation of differentiated progeny (Loh et al., 2009). JMML constitutes approximately 30% of childhood cases of myelodysplastic syndrome and 2% of leukemia (Hasle et al., 1999). Although JMML is a progressive and often rapidly fatal disease without hematopoietic stem cell transplantation (HSCT), some patients have been shown to have a prolonged and stable clinical course without HSCT (Niemeyer et al., 1997). Chronic myelomonocytic leukemia (CMML) is a similar disorder with later onset. Both JMML and CMML have a high frequency of mutations affecting the RAS signaling pathway and show hypersensitivity to stimulation with GM-CSF, which causes STAT5 (601511) hyperphosphorylation (Loh et al., 2009). Genetic Heterogeneity of Juvenile Myelomonocytic Leukemia In up to 60% of cases of JMML, the RAS/MAPK pathway is deregulated due to somatic mutations in the PTPN11 (176876), KRAS (190070), and NRAS (164790) genes. Additionally, both germline and somatic mutations in the CBL gene have been found in patients with JMML, indicating a frequency of 10 to 15% of JMML patients overall (Loh et al., 2009). Somatic disruptions of the GRAF gene (ARHGAP26; 605370) have also been found in patients with JMML. About 10 to 15% of JMML cases arise in children with neurofibromatosis type I (NF1; 162200) due to germline mutations in the NF1 gene (613113). In addition, patients with Noonan syndrome (NS1, 163950; NS3, 609942) or Noonan syndrome-like disorder (NSLL; 613563) due to germline mutations in the PTPN11, KRAS2, and CBL genes, respectively, also have an increased risk of developing JMML. Genetic Heterogeneity of Chronic Myelomonocytic Leukemia Somatic mutations in the CBL, ASXL1 (612990), TET2 (612839), and SF3B1 (605590) genes have been found in patients with CMML. [from OMIM]

Watson syndrome (WTSN) is an autosomal dominant disorder characterized by pulmonic stenosis, cafe-au-lait spots, decreased intellectual ability (Watson, 1967), and short stature (Partington et al., 1985). Most affected individuals have relative macrocephaly and Lisch nodules and about one-third of those affected have neurofibroma (Allanson et al., 1991). [from OMIM]

Neurofibromatosis 1 (NF1) is a multisystem disorder characterized by multiple café au lait macules, intertriginous freckling, multiple cutaneous neurofibromas, and learning disability or behavior problems. About half of people with NF1 have plexiform neurofibromas, but most are internal and not suspected clinically. Plexiform neurofibromas can cause pain, neurologic deficits, and abnormalities of involved or adjacent structures. Less common but potentially more serious manifestations include optic nerve and other central nervous system gliomas, malignant peripheral nerve sheath tumors, scoliosis, tibial dysplasia, vasculopathy, and gastrointestinal, endocrine, or pulmonary disease. [from GeneReviews]