MedGen

Cerebral cavernous malformations (CCMs) are vascular malformations in the brain and spinal cord comprising closely clustered, enlarged capillary channels (caverns) with a single layer of endothelium without mature vessel wall elements or normal intervening brain parenchyma. The diameter of CCMs ranges from a few millimeters to several centimeters. CCMs increase or decrease in size and increase in number over time. Hundreds of lesions may be identified, depending on the person's age and the quality and type of brain imaging used. Although CCMs have been reported in infants and children, the majority become evident between the second and fifth decades with findings such as seizures, focal neurologic deficits, nonspecific headaches, and cerebral hemorrhage. Up to 50% of individuals with FCCM remain symptom free throughout their lives. Cutaneous vascular lesions are found in 9% of those with familial cerebral cavernous malformations (FCCM; see Diagnosis/testing) and retinal vascular lesions in almost 5%. [from GeneReviews]

Noonan syndrome (NS) is characterized by characteristic facies, short stature, congenital heart defect, and developmental delay of variable degree. Other findings can include broad or webbed neck, unusual chest shape with superior pectus carinatum and inferior pectus excavatum, cryptorchidism, varied coagulation defects, lymphatic dysplasias, and ocular abnormalities. Although birth length is usually normal, final adult height approaches the lower limit of normal. Congenital heart disease occurs in 50%-80% of individuals. Pulmonary valve stenosis, often with dysplasia, is the most common heart defect and is found in 20%-50% of individuals. Hypertrophic cardiomyopathy, found in 20%-30% of individuals, may be present at birth or develop in infancy or childhood. Other structural defects include atrial and ventricular septal defects, branch pulmonary artery stenosis, and tetralogy of Fallot. Up to one fourth of affected individuals have mild intellectual disability, and language impairments in general are more common in NS than in the general population. [from GeneReviews]

Houge-Janssens syndrome-3 (HJS3) is characterized by global developmental delay apparent from infancy. The phenotype is highly variable: patients may have hypotonia, behavioral abnormalities, and abnormalities on brain imaging, including enlarged ventricles, thin corpus callosum, and sometimes small brainstem. Many develop seizures, sometimes refractory, and some may have nonspecific dysmorphic features. Intellectual impairment can vary from mild to profound, and some patients may benefit from special education and respond well to speech therapy (summary by Reynhout et al., 2019). For a discussion of genetic heterogeneity of HJS, see HJS1 (616355). [from OMIM]

Any gingival fibromatosis in which the cause of the disease is a mutation in the SOS1 gene. [from MONDO]

Schimmelpenning-Feuerstein-Mims syndrome, also known as linear sebaceous nevus syndrome, is characterized by sebaceous nevi, often on the face, associated with variable ipsilateral abnormalities of the central nervous system, ocular anomalies, and skeletal defects (summary by Happle, 1991 and Ernst et al., 2007). The linear sebaceous nevi follow the lines of Blaschko (Hornstein and Knickenberg, 1974; Bouwes Bavinck and van de Kamp, 1985). All cases are sporadic. The syndrome is believed to be caused by an autosomal dominant lethal mutation that survives by somatic mosaicism (Gorlin et al., 2001). [from OMIM]

Hyperphosphatemic familial tumoral calcinosis is a rare autosomal recessive metabolic disorder characterized by the progressive deposition of basic calcium phosphate crystals in periarticular spaces, soft tissues, and sometimes bone (Chefetz et al., 2005). The biochemical hallmark of tumoral calcinosis is hyperphosphatemia caused by increased renal absorption of phosphate due to loss-of-function mutations in the FGF23 or GALNT3 (601756) gene. The term 'hyperostosis-hyperphosphatemia syndrome' is sometimes used when the disorder is characterized by involvement of the long bones associated with the radiographic findings of periosteal reaction and cortical hyperostosis. Although some have distinguished HHS from FTC by the presence of bone involvement and the absence of skin involvement (Frishberg et al., 2005), Ichikawa et al. (2010) concluded that the 2 entities represent a continuous spectrum of the same disease, best described as familial hyperphosphatemic tumoral calcinosis. HFTC is considered to be the clinical converse of autosomal dominant hypophosphatemic rickets (ADHR; 193100), an allelic disorder caused by gain-of-function mutations in the FGF23 gene and associated with hypophosphatemia and decreased renal phosphate absorption (Chefetz et al., 2005; Ichikawa et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of HFTC, see 211900. [from OMIM]

Noonan syndrome (NS) is characterized by characteristic facies, short stature, congenital heart defect, and developmental delay of variable degree. Other findings can include broad or webbed neck, unusual chest shape with superior pectus carinatum and inferior pectus excavatum, cryptorchidism, varied coagulation defects, lymphatic dysplasias, and ocular abnormalities. Although birth length is usually normal, final adult height approaches the lower limit of normal. Congenital heart disease occurs in 50%-80% of individuals. Pulmonary valve stenosis, often with dysplasia, is the most common heart defect and is found in 20%-50% of individuals. Hypertrophic cardiomyopathy, found in 20%-30% of individuals, may be present at birth or develop in infancy or childhood. Other structural defects include atrial and ventricular septal defects, branch pulmonary artery stenosis, and tetralogy of Fallot. Up to one fourth of affected individuals have mild intellectual disability, and language impairments in general are more common in NS than in the general population. [from GeneReviews]

Noonan syndrome with multiple lentigines (NSML) is a condition in which the cardinal features consist of lentigines, hypertrophic cardiomyopathy, short stature, pectus deformity, and dysmorphic facial features including widely spaced eyes and ptosis. Multiple lentigines present as dispersed flat, black-brown macules, mostly on the face, neck, and upper part of the trunk with sparing of the mucosa. In general, lentigines do not appear until age four to five years but then increase to the thousands by puberty. Some individuals with NSML do not exhibit lentigines. Approximately 85% of affected individuals have heart defects, including hypertrophic cardiomyopathy (typically appearing during infancy and sometimes progressive) and pulmonary valve stenosis. Postnatal growth restriction resulting in short stature occurs in fewer than 50% of affected persons, although most affected individuals have a height that is less than the 25th centile for age. Sensorineural hearing deficits, present in approximately 20% of affected individuals, are poorly characterized. Intellectual disability, typically mild, is observed in approximately 30% of persons with NSML. [from GeneReviews]

Immune dysregulation, autoimmunity, and autoinflammation (IDAA) is an immunologic disorder characterized by anemia and thrombocytopenia associated with circulating autoantibodies, positive Coombs test, and increased levels of proinflammatory cytokines due to constitutive activation of immune-related signaling pathways (Tao et al., 2023). [from OMIM]

Thrombocytopenia-6 is an autosomal dominant hematologic disorder characterized by increased bleeding episodes due to reduced platelet count and abnormal platelet morphology resulting from defective megakaryopoiesis. Patients may also have bone abnormalities, including osteoporosis or tooth loss, as well as an increased risk for myelofibrosis (summary by Turro et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of thrombocytopenia, see 313900. [from OMIM]

Nonmedullary thyroid cancer (NMTC) comprises thyroid cancers of follicular cell origin and accounts for more than 95% of all thyroid cancer cases. The remaining cancers originate from parafollicular cells (medullary thyroid cancer, MTC; 155240). NMTC is classified into 4 groups: papillary, follicular, Hurthle cell (607464), and anaplastic. Approximately 5% of NMTC is hereditary, occurring as a minor component of a familial cancer syndrome (e.g., familial adenomatous polyposis, 175100, Carney complex, 160980) or as a primary feature (familial NMTC or FNMTC). Papillary thyroid cancer (PTC) is the most common histologic subtype of FNMTC, accounting for approximately 85% of cases (summary by Vriens et al., 2009). Follicular thyroid cancer (FTC) accounts for approximately 15% of NMTC and is defined by invasive features that result in infiltration of blood vessels and/or full penetration of the tumor capsule, in the absence of the nuclear alterations that characterize papillary carcinoma. FTC is rarely multifocal and usually does not metastasize to the regional lymph nodes but tends to spread via the bloodstream to the lung and bones. An important histologic variant of FTC is the oncocytic (Hurthle cell, oxyphilic) follicular carcinoma composed of eosinophilic cells replete with mitochondria (summary by Bonora et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of NMTC, see NMTC1 (188550). [from OMIM]

PPP2R1A-related neurodevelopmental disorder (NDD) is characterized by: severe, persistent hypotonia; developmental delay with variable intellectual outcomes, typically in the moderate-to-severe intellectual disability range; seizures (more commonly seen in individuals with microcephaly and/or severe intellectual disability); attention-deficit/hyperactivity disorder and other behavioral problems (anxiousness, repetitive movements, self-injurious or destructive behavior, and autism spectrum disorder); feeding and swallowing issues; and dysmorphic features of the head and face. A minority of affected individuals have ear anomalies, hearing loss, ptosis, generalized joint hypermobility, and patent ductus arteriosus. Brain MRI findings are nonspecific but typically include complete or partial agenesis of the corpus callosum. Nonprogressive ventriculomegaly may be seen in a subset of affected individuals and is often associated with specific pathogenic variants in PPP2R1A: c.544C>T (p.Arg182Trp) and c.547C>T (p.Arg183Trp). [from GeneReviews]

Any IgA glomerulonephritis in which the cause of the disease is a mutation in the SPRY2 gene. [from MONDO]

Dabrafenib is a kinase inhibitor used in the treatment of individuals with unresectable or metastatic melanoma, metastatic non-small cell lung cancer (NSCLC), locally advanced or metastatic anaplastic thyroid cancer (ATC), pediatric low-grade glioma (LGG), and other unresectable or metastatic solid tumors with specific BRAF variants. Dabrafenib can be used as a single agent to treat melanoma with the BRAF valine 600 to glutamic acid (V600E) variant or in combination with the MEK inhibitor trametinib to treat multiple tumor types with BRAF V600E or V600K variants.The BRAF protein is an intracellular kinase in the mitogen-activated protein kinases (MAPK) pathway. Functionally, BRAF regulates essential cell processes such as cell growth, division, differentiation, and apoptosis. The gene BRAF is also a proto-oncogene—when mutated, it transforms normal cells into cancerous cells. Variation in the kinase domain of BRAF is associated with various cancers. The most common BRAF variant, V600E, constitutively activates the kinase and causes cell proliferation in the absence of growth factors that would usually be needed. The V600E variant is detected in approximately 50% of melanomas, 25% of ATC, 2% of NSCLC, and 20% of pediatric LGGs. The FDA-approved label for dabrafenib states that the presence of BRAF mutation in tumor specimens (V600E for dabrafenib monotherapy; V600E or V600K for dabrafenib plus trametinib) should be confirmed using an FDA-approved test before starting treatment with dabrafenib. Dabrafenib is not indicated for the treatment of individuals with wild-type BRAF tumors, or the treatment of colorectal cancer due to intrinsic resistance to BRAF inhibitor monotherapy. The label also states that individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency should be monitored for signs of hemolytic anemia while taking dabrafenib (1). However, it is important to note that an independent literature review by the Clinical Pharmacogenetics Implementation Consortium found no publications to support or refute this risk and thus issued no guidance for G6PD deficiency and dabrafenib therapy. [from Medical Genetics Summaries]

Vemurafenib is a kinase inhibitor used in the treatment of patients with unresectable or metastatic melanoma with the BRAF V600E variant. BRAF is an intracellular kinase in the mitogen-activated protein kinases (MAPK) pathway. BRAF is involved in regulating important cell functions such as cell growth, division, differentiation, and apoptosis. BRAF is also a proto-oncogene—when mutated it has the ability to transform normal cells into cancerous cells. Variation in the kinase domain of BRAF have been associated with various cancers. The most common BRAF variant, V600E, constitutively activates the kinase, and causes cell proliferation in the absence of growth factors that would normally be required. The V600E variant is detected in approximately 50% of melanomas. The FDA-approved drug label for vemurafenib states that the presence of BRAF V600E mutation in tumor specimens should be confirmed, using an FDA-approved test, before starting treatment with vemurafenib. The label also states that vemurafenib is not indicated for treatment of patients with wild-type BRAF melanoma. Variations in NRAS, also an oncogene, are found in up to 30% of all malignancies and in approximately 15-20% of melanomas. NRAS variants activate MAPK and have been implicated in in acquired resistance to BRAF inhibitors. Vemurafenib’s label warns that one adverse effect associated with therapy may be the progression of pre-existing chronic myelomonocytic leukemia with NRAS mutation. Other adverse effects include arthralgia, rash, alopecia, photosensitivity reaction, pruritus, and skin papilloma. [from Medical Genetics Summaries]

Immunodeficiency-36 with lymphoproliferation (IMD36) is an autosomal dominant primary immunodeficiency with a highly heterogeneous clinical phenotype, characterized primarily by recurrent respiratory tract infections, lymphoproliferation, and antibody deficiency. Other features include growth retardation, mild neurodevelopmental delay, and autoimmunity. The major complication is development of B-cell lymphoma (Elkaim et al., 2016). [from OMIM]

Cardiofaciocutaneous (CFC) syndrome is characterized by cardiac abnormalities (pulmonic stenosis and other valve dysplasias, septal defects, hypertrophic cardiomyopathy, rhythm disturbances), distinctive craniofacial appearance, and cutaneous abnormalities (including xerosis, hyperkeratosis, ichthyosis, keratosis pilaris, ulerythema ophryogenes, eczema, pigmented moles, hemangiomas, and palmoplantar hyperkeratosis). The hair is typically sparse, curly, fine or thick, woolly or brittle; eyelashes and eyebrows may be absent or sparse. Nails may be dystrophic or fast growing. Some form of neurologic and/or cognitive delay (ranging from mild to severe) is seen in all affected individuals. Neoplasia, mostly acute lymphoblastic leukemia, has been reported in some individuals. [from GeneReviews]

Renal hypodysplasia/aplasia belongs to a group of perinatally lethal renal diseases, including bilateral renal aplasia, unilateral renal agenesis with contralateral dysplasia (URA/RD), and severe obstructive uropathy. Renal aplasia falls at the most severe end of the spectrum of congenital anomalies of the kidney and urinary tract (CAKUT; 610805), and usually results in death in utero or in the perinatal period. Families have been documented in which bilateral renal agenesis or aplasia coexists with unilateral renal aplasia, renal dysplasia, or renal aplasia with renal dysplasia, suggesting that these conditions may belong to a pathogenic continuum or phenotypic spectrum (summary by Joss et al., 2003; Humbert et al., 2014). For a discussion of genetic heterogeneity of renal hypodysplasia/aplasia, see RHDA1 (191830). [from OMIM]

Cardiofaciocutaneous (CFC) syndrome is characterized by cardiac abnormalities (pulmonic stenosis and other valve dysplasias, septal defects, hypertrophic cardiomyopathy, rhythm disturbances), distinctive craniofacial appearance, and cutaneous abnormalities (including xerosis, hyperkeratosis, ichthyosis, keratosis pilaris, ulerythema ophryogenes, eczema, pigmented moles, hemangiomas, and palmoplantar hyperkeratosis). The hair is typically sparse, curly, fine or thick, woolly or brittle; eyelashes and eyebrows may be absent or sparse. Nails may be dystrophic or fast growing. Some form of neurologic and/or cognitive delay (ranging from mild to severe) is seen in all affected individuals. Neoplasia, mostly acute lymphoblastic leukemia, has been reported in some individuals. [from GeneReviews]

Isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) is characterized by inappropriately low serum concentrations of the gonadotropins LH (luteinizing hormone) and FSH (follicle-stimulating hormone) in the presence of low circulating concentrations of sex steroids. IGD is associated with a normal sense of smell (normosmic IGD) in approximately 40% of affected individuals and an impaired sense of smell (Kallmann syndrome) in approximately 60%. IGD can first become apparent in infancy, adolescence, or adulthood. Infant boys with congenital IGD often have micropenis and cryptorchidism. Adolescents and adults with IGD have clinical evidence of hypogonadism and incomplete sexual maturation on physical examination. Adult males with IGD tend to have prepubertal testicular volume (i.e., <4 mL), absence of secondary sexual features (e.g., facial and axillary hair growth, deepening of the voice), decreased muscle mass, diminished libido, erectile dysfunction, and infertility. Adult females have little or no breast development and primary amenorrhea. Although skeletal maturation is delayed, the rate of linear growth is usually normal except for the absence of a distinct pubertal growth spurt. [from GeneReviews]