MedGen

Gliomas are central nervous system neoplasms derived from glial cells and comprise astrocytomas, glioblastoma multiforme, oligodendrogliomas, ependymomas, and subependymomas. Glial cells can show various degrees of differentiation even within the same tumor (summary by Kyritsis et al., 2010). Ependymomas are rare glial tumors of the brain and spinal cord (Yokota et al., 2003). Subependymomas are unusual tumors believed to arise from the bipotential subependymal cell, which normally differentiates into either ependymal cells or astrocytes. They were characterized as a distinct entity by Scheinker (1945). They tend to be slow-growing, noninvasive, and located in the ventricular system, septum pellucidum, cerebral aqueduct, or proximal spinal cord (summary by Ryken et al., 1994). Gliomas are known to occur in association with several other well-defined hereditary tumor syndromes such as mismatch repair cancer syndrome (see 276300), melanoma-astrocytoma syndrome (155755), neurofibromatosis-1 (NF1; 162200) and neurofibromatosis-2 (see SWNV, 101000), and tuberous sclerosis (TSC1; 191100). Familial clustering of gliomas may occur in the absence of these tumor syndromes, however. Genetic Heterogeneity of Susceptibility to Glioma Other glioma susceptibilities include GLM2 (613028), caused by variation in the PTEN gene (601728) on chromosome 10q23; GLM3 (613029), caused by variation in the BRCA2 gene (600185) on chromosome 13q13; GLM4 (607248), mapped to chromosome 15q23-q26.3; GLM5 (613030), mapped to chromosome 9p21; GLM6 (613031), mapped to chromosome 20q13; GLM7 (613032), mapped to chromosome 8q24; GLM8 (613033), mapped to chromosome 5p15; and GLM9, caused by variation in the POT1 gene (606478) on chromosome 7q31. Somatic mutation, disruption, or copy number variation of the following genes or loci may also contribute to the formation of glioma: ERBB (EGFR; 131550), ERBB2 (164870), LGI1 (604619), GAS41 (602116), GLI (165220), DMBT1 (601969), IDH1 (147700), IDH2 (147650), BRAF (164757), PARK2 (602544), TP53 (191170), RB1 (614041), PIK3CA (171834), 10p15, 19q, and 17p13.3. [from OMIM]

In a review article on the genetic predisposition to gastric cancer, Bevan and Houlston (1999) concluded that several genes may be associated with an increased risk of gastric cancer. Gastric cancer is a manifestation of a number of inherited cancer predisposition syndromes, including hereditary nonpolyposis colon cancer (HNPCC1; see 120435), familial adenomatous polyposis (FAP; 175100), Peutz-Jeghers syndrome (PJS; 175200), Cowden disease (CD; 158350), the Li-Fraumeni syndrome (151623), and diffuse gastric and lobular breast cancer syndrome (DGLBC; 137215). Canedo et al. (2007) provided a review of genetic susceptibility to gastric cancer in patients infected with Helicobacter pylori (see 600263). [from OMIM]

A tumor (abnormal growth of tissue) of the ovary. [from HPO]

Brachydactyly type B2 (BDB2) is a subtype of brachydactyly characterized by hypoplasia/aplasia of distal phalanges in combination with distal symphalangism, fusion of carpal/tarsal bones, and partial cutaneous syndactyly (summary by Lehmann et al., 2007). [from OMIM]

Cetuximab is a monoclonal antibody used in the treatment of metastatic colorectal cancer (mCRC) and cancer of the head and neck. Cetuximab is an epidermal growth factor receptor (EGFR) antagonist, which works by blocking the growth of cancer cells. It is administered as a weekly intravenous (IV) infusion, but in practice, is often given every other week to coincide with chemotherapy (for example, FOLFIRI or FOLFOX). Cetuximab has several off-label uses as well, which include non-small cell lung cancer, squamous cell carcinoma of the skin, and Menetrier’s disease. Interestingly, for colorectal cancer, the location of the primary tumor influences whether an individual with mCRC will respond to anti-EGFR therapy, and influences prognosis. Individuals with left-sided tumors are more likely to respond well to anti-EGFR therapy and have a better prognosis. Individuals with right-sided tumors have a worse prognosis and respond poorly to anti-EGFR therapy. However, currently only the mutation status of the tumor, and not the location of the tumor, is discussed in the drug label’s dosing recommendations. Resistance to cetuximab is associated with specific RAS mutations. The RAS family of oncogenes includes the KRAS and NRAS genes. When mutated, these genes have the ability to transform normal cells into cancerous cells. The KRAS mutations are particularly common, being detectable in 40% of metastatic colorectal tumors. The KRAS mutations often lead to constitutive activation of the mitogen-activated protein kinase (MAPK) pathway and are associated with resistance to anti-EGFR drugs such as cetuximab. In addition, mutations in NRAS and another gene, BRAF, have been associated with poor response to anti-EGFR therapy; however, BRAF mutation does not explicitly preclude anti-EGFR therapy. Combination therapies targeting both BRAF and EGFR have shown to improve survival for individuals with wild-type RAS and mutant BRAF. The 2018 FDA-approved drug label for cetuximab states that for mCRC, cetuximab is indicated for K- and N-RAS wild-type (no mutation), EGFR-expressing tumors. The label states that an FDA-approved test must be used to confirm the absence of a RAS mutation (in either KRAS or NRAS) prior to starting cetuximab. While the FDA label also states that EGFR expression should also be confirmed by an approved test prior to starting therapy for mCRC, this is largely not implemented in practice, nor is it recommended by professional oncology society guidelines. Similarly, the 2015 Update from the American Society of Clinical Oncology (ASCO) states that anti-EGFR therapy should only be considered for the treatment of individuals whose tumor is determined to not have mutations detected after extended RAS testing. The 2020 National Comprehensive Cancer Network (NCCN) guideline also strongly recommends KRAS/NRAS genotyping of tumor tissue in all individuals with mCRC. In addition, the guideline states the V600E mutation in the BRAF gene makes a response to cetuximab (and panitumumab) highly unlikely unless given a BRAF inhibitor. [from Medical Genetics Summaries]

MDDGB2 is an autosomal recessive congenital muscular dystrophy associated with impaired intellectual development and mild structural brain abnormalities (Yanagisawa et al., 2007). It is part of a group of similar disorders, collectively known as 'dystroglycanopathies,' resulting from defective glycosylation of alpha-dystroglycan (DAG1; 128239) (Godfrey et al., 2007). For a discussion of genetic heterogeneity of congenital muscular dystrophy-dystroglycanopathy type B, see MDDGB1 (613155). [from OMIM]

Panitumumab is a monoclonal antibody used for the treatment of metastatic colorectal cancer (mCRC). Panitumumab is an epidermal growth factor receptor (EGFR) antagonist, which works by blocking the growth of cancer cells. It is administered every 14 days as an intravenous (IV) infusion, often with chemotherapy. Panitumumab is approved for first-line therapy with folinic acid, fluorouracil, and oxaliplatin (FOLFOX) and as monotherapy following disease progression after prior treatment with fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy. The location of the primary tumor correlates whether an individual with mCRC is likely respond to anti-EGFR therapy. Individuals with left-sided tumors are more likely to respond well to anti-EGFR therapy and have a better prognosis. Individuals with right-sided tumors have a worse prognosis and respond poorly to anti-EGFR therapy. However, only the genetic variation status of the tumor, and not the location of the tumor, is discussed in the FDA drug label’s dosing recommendations. Resistance to panitumumab is associated with specific RAS mutations. The RAS is a family of oncogenes that includes the KRAS and NRAS genes. When mutated, these genes have the ability to transform normal cells into cancerous cells by providing a continual growth stimulus to cells. The KRAS mutations are particularly common, being detectable in 40% of metastatic colorectal tumors. The KRAS mutations often lead to constitutive activation of the EGFR and are associated with resistance to anti-EGFR drugs such as panitumumab. Mutations in NRAS and another gene, BRAF, have also been associated with poor response to anti-EGFR therapy. The 2017 FDA-approved label states that panitumumab is indicated for wild-type RAS (no mutations in either KRAS or NRAS) mCRC. The label states that an FDA-approved test must be used to confirm the absence of RAS mutations before starting panitumumab, and that panitumumab is not indicated for the treatment of individuals with colorectal cancer with RAS mutations (in either NRAS or KRAS), or when the RAS genetic variation status is unknown. Similarly, the 2015 Update from the American Society of Clinical Oncology (ASCO) states that anti-EGFR therapy should only be considered for the treatment of individuals whose tumor is determined to not have variations detected after extended RAS testing. The 2020 National Comprehensive Cancer Network (NCCN) guideline also strongly recommends KRAS/NRAS genotyping of tumor tissue in all individuals with mCRC. In addition, the guideline states the V600E mutation in the BRAF gene makes a response to panitumumab highly unlikely, unless given with a BRAF inhibitor. [from Medical Genetics Summaries]

Trastuzumab is a monoclonal antibody used in the treatment of breast and gastric/gastroesophageal cancer. It targets an epidermal growth factor receptor encoded by the ERBB2 gene, which is commonly referred to as the HER2 gene. Multiple biosimilar products to Herceptin are now available: Kanjinti, Trazimera, Ontruzant, Herzuma and Ogivri. The ERBB2 gene is overexpressed in 15–20% of breast cancers and 15–20% of gastric and esophageal cancers. Overall, “HER2 positive” tumors are associated with a faster rate of growth and—in some cases—a poorer prognosis in absence of anti-HER2 therapy. The use of trastuzumab in treatment regimens improves outcomes, with limited adverse effects that include cardiac toxicity. The FDA-approved drug label states that trastuzumab should only be used to treat individuals with tumors that have either HER2 protein overexpression or ERBB2 gene amplification, as determined by an accurate and validated FDA-approved assay, specific for the type of tumor tested (breast or gastric). The FDA-approved drug label for all trastuzumab biosimilars describes only the use of trastuzumab in adjuvant treatment of breast cancer, though its efficacy in neoadjuvant care for breast cancer and esophageal adenocarcinoma has also been documented. The most recent update (2018) of the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines continues to state that all newly diagnosed individuals with breast cancer must have an HER2 test performed. Individuals who then develop metastatic disease must have an HER2 test performed in a metastatic site, if tissue sample is available. [from Medical Genetics Summaries]

Any amyotrophic lateral sclerosis in which the cause of the disease is a mutation in the ERBB4 gene. [from MONDO]

Charcot-Marie-Tooth disease type 2B2 (CMT2B2) is an autosomal recessive sensorineural axonal peripheral neuropathy manifest as distal muscle weakness and atrophy and distal sensory impairment. The disorder predominantly affects the lower limbs, resulting in gait impairment, although upper limb and hand involvement also occurs. The age at onset and severity is variable: most have onset in the third decade, although earlier onset has been reported. The disorder is slowly progressive, and some patients may lose independent ambulation later in life. More variable features may include ataxia, dysarthria, cerebellar atrophy, and eye movement abnormalities (summary by Leal et al., 2018). For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT type 2, see CMT2A1 (118210). [from OMIM]

Familial erythroleukemia (FERLK) is a leukemic or preleukemic state in which red cell proliferation is the predominant feature. Hematologic characteristics include particularly ineffective and hyperplastic erythropoiesis with megaloblastic components accompanied by myeloblastic proliferation of varying degree (Park et al., 2002). Park et al. (2002) discussed the evolution of the definition of 'erythroleukemia,' which is considered by most to be a subtype of acute myelogenous leukemia (AML; 601626). Controversy about the precise definition of erythroleukemia revolves around the number or percentage of erythroblasts and myeloblasts found in the bone marrow and peripheral circulation. In the French-American-British (FAB) classification system (Bennett et al., 1985), it is known as AML-M6, whereas in the revised World Health Organization (WHO) classification system (Harris et al., 1999), it is known as 'AML, not otherwise categorized' (Zini and D'Onofrio, 2004). [from OMIM]

Pertuzumab is a monoclonal antibody used in the treatment of breast cancer. Pertuzumab was designed to target an epidermal growth factor receptor encoded by the ERBB2 gene, commonly referred to as the HER2 gene. The ERBB2 gene is overexpressed in 15–20% of breast cancers and is also overexpressed in some cases of other cancer types (gastric, colon, head, and neck). Historically, “HER2-positive” tumors are associated with a faster rate of growth and a poorer prognosis than other breast cancer subtypes. The use of pertuzumab in treatment regimens improves outcomes, with limited adverse effects that include cardiac toxicity. Pertuzumab is used with other drugs as an advanced breast cancer treatment, a neoadjuvant treatment, and an adjuvant treatment for HER2-positive breast cancer. In the advanced/metastatic setting, pertuzumab added to trastuzumab and a taxane is used to increase long-term progression-free and overall survival when administered in the first line setting. As neoadjuvant treatment, pertuzumab is given with trastuzumab and chemotherapy before surgery in individuals with early breast cancer to increase pathologic complete response rates. And as an adjuvant treatment, pertuzumab is given with trastuzumab and chemotherapy to reduce the risk of cancer reoccurrence in individuals with early breast cancer. The 2020 FDA-approved drug label states that pertuzumab should only be used to treat individuals with tumors that have either HER2 protein overexpression or ERBB2 gene amplification, as determined by an accurate and validated FDA-approved assay. This is because these are the only individuals studied for whom benefit has been shown. The most recent update (2018) American Society of Clinical Oncology (ASCO) / College of American Pathologists (CAP) guidelines continue to state that all newly diagnosed individuals with breast cancer must have an HER2 test performed. Individuals who then develop metastatic disease must have an HER2 test performed in a metastatic site, if a tissue sample is available. [from Medical Genetics Summaries]

Lethal congenital contracture syndrome-2 (LCCS2) is an autosomal recessive disorder characterized by severe multiple congenital contractures with muscle wasting and atrophy. Micrognathia and other craniofacial anomalies, including cleft palate, as well as cardiac defects and enlarged urinary bladder at birth have also been reported. Hydrops fetalis and multiple pterygia are absent. Most patients have died in the neonatal period, although 2 survived to early adolescence (Landau et al., 2003). For a general phenotypic description and a discussion of genetic heterogeneity of LCCS, see LCCS1 (253310). [from OMIM]

Mutations in the CRYBB2 gene have been found to cause several types of cataract, which have been described as congenital cerulean, 'blue dot,' Coppock-like, sutural with punctate and cerulean opacities, pulverulent embryonal, pulverulent with cortical opacities, dense posterior star-shaped subcapsular with pulverulent opacities in the cortical and embryonal regions, and dense embryonal. Before it was known that mutations in the CRYBB2 gene cause several types of cataract, the preferred title of this entry was 'Cataract, Congenital, Cerulean Type 2,' with the symbol CCA2. [from OMIM]

Autosomal recessive familial visceral neuropathy-1 (VSCN1) is characterized by a broad spectrum of developmental anomalies associating neural crest and extraneural crest features, including intestinal dysmotility due to aganglionosis (Hirschsprung disease), hypoganglionosis, and/or chronic intestinal pseudoobstruction. Some patients develop progressive peripheral neuropathy, and arthrogryposis has been observed. Hypoplasia or aplasia of the olfactory bulb and of the external auditory canals, as well as microtia or anotia, have been reported. Patients also exhibit facial dysmorphisms, including microretrognathia in most; other variable features include structural cardiac anomalies and arthrogryposis with multiple pterygia (Le et al., 2021). Genetic Heterogeneity of Familial Visceral Neuropathy Autosomal recessive familial visceral neuropathy-2 (VSCN2; 619465) is caused by mutation in the ERBB2 gene (164870) on chromosome 17q12. Also see VSCN3 (609629) for an autosomal dominant form of the disorder. [from OMIM]

Autosomal recessive visceral neuropathy-2 (VSCN2) is characterized by intestinal dysmotility due to aganglionosis or hypoganglionosis of the colon. Patients also exhibit peripheral axonal neuropathy, ptosis, and sensorineural hearing loss (Le et al., 2021). For a discussion of genetic heterogeneity of VSCN, see VSCN1 (243180). [from OMIM]

An epithelial neoplasm arising from the thymus. It may be associated with myasthenia gravis, pure red cell aplasia, and hypogammaglobulinemia. It includes thymoma type B1 which is a thymoma of low grade malignant potential, thymoma type B2 which is a thymoma of moderate malignancy, and thymoma type B3 which is also known as well differentiated thymic carcinoma. [from NCI]

Hereditary angioedema-4 (HAE4) is an autosomal dominant disorder characterized by episodic subcutaneous or submucosal edema with onset usually in adulthood. Swelling most commonly involves the face and tongue, sometimes resulting in occlusion of the airway, which can cause death. The larynx, abdomen, and limbs may also be involved. Circulating C1 inhibitor (C1INH) levels and function, as well as plasminogen levels and activity, are normal. Although the disorder is autosomal dominant, there is evidence of incomplete penetrance, variable expressivity, and female predominance. The episodes may be triggered by stress, oral contraceptives, ACE inhibitors, and angiotensin II receptor blockades. The pathogenesis is believed to be due to altered plasmin function resulting in enhanced release of bradykinin. Successful clinical management has been achieved with tranexamic acid, which inhibits plasmin, and icatibant, a selective bradykinin B2 receptor (113503) antagonist (summary by Farkas et al., 2021). For a discussion of genetic heterogeneity of HAE, see 106100. [from OMIM]

A rare genetic neurological disorder with characteristics of childhood-onset severe myoclonic and tonic-clonic seizures and early-onset ataxia leading to severe gait disturbances associated with normal to slightly diminished cognition. Scoliosis, diffuse muscle atrophy and subcutaneous fat loss, as well as developmental delay, may be associated. Brain MRI may reveal complete agenesis of the corpus callosum, ventriculomegaly, interhemispheric cysts and simplified gyration (frontally). [from SNOMEDCT_US]

A thymic epithelial neoplasm characterized by the presence of neoplastic large, polygonal epithelial cells with large vesicular nuclei and prominent nucleoli. The neoplastic cells are arranged around perivascular spaces and along septa. Immature T-lymphocytes are also present. It may be associated with myasthenia gravis, pure red cell aplasia, and hypogammaglobulinemia. It is a tumor of moderate malignancy. The majority of cases occur in the anterior mediastinum as Masaoka stage I, stage II, or stage III tumors. Metastatic, stage IV tumors occur less frequently. [from NCI]