MedGen

Immunodeficiency-79 (IMD79) is an autosomal recessive disorder characterized by childhood onset of recurrent and recalcitrant skin warts due to uncontrolled viral infection with human papillomavirus (HPV). Some patients may also have recurrent respiratory infections beginning in childhood, but the phenotype overall is mild compared to other primary immunodeficiencies. Patients may not come to attention until adulthood. Laboratory studies show absence of the CD4 antigen on T cells, monocytes, and dendritic cells, with variable secondary abnormalities in B cells and NK cells due to lack of CD4+ T cells (summary by Lisco et al., 2021). [from OMIM]

Immunodeficiency-69 (IMD69) is an autosomal recessive disorder characterized by increased susceptibility to disseminated mycobacterial infection, including after BCG (bacille Calmette-Guerin) vaccination. Affected individuals develop fever, hepatosplenomegaly, leukocytosis, and thrombocytosis during the acute infection. There appears to be normal immunologic function against other pathogens, including viruses and bacteria. Immunologic work-up shows normal parameters, but patient T and NK cells fail to produce gamma-interferon (IFNG) when stimulated in vitro (summary by Kerner et al., 2020). IMD69 is a form of mendelian susceptibility to mycobacterial disease (MSMD) (see, e.g., IMD27A; 209950). [from OMIM]

Thrombocythemia, or thrombocytosis, is a myeloproliferative disorder characterized by excessive platelet production resulting in increased numbers of circulating platelets. Thrombocythemia can be associated with thrombotic or hemorrhagic episodes and occasional leukemic transformation (summary by Wiestner et al., 1998). Genetic Heterogeneity of Thrombocythemia THCYT2 (601977) is caused by germline or somatic mutation in the THPO receptor gene (MPL; 159530) on chromosome 1p34, and THCYT3 (614521) is caused by germline or somatic mutation in the JAK2 gene (147796) on chromosome 9p. Somatic mutations in the TET2 (612839), ASXL1 (612990), SH2B3 (605093), and SF3B1 (605590) genes have also been found in cases of essential thrombocythemia. Somatic mutation in the CALR gene (109091) occurs in approximately 70% of essential thrombocythemia patients who lack JAK2 and MPL mutations (Klampfl et al., 2013; Nangalia et al., 2013). [from OMIM]

Carbamazepine is an aromatic anticonvulsant used to treat epilepsy and other seizure disorders, as well as bipolar disorder and trigeminal neuralgia. Carbamazepine can cause a variety of cutaneous adverse reactions, ranging from mild maculopapular eruptions to Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). The genetic variant HLA-B*15:02 is associated with the risk of SJS/TEN. Patients who have at least one copy of the HLA-B*15:02 allele (considered HLA-B*15:02-positive) have a significantly increased risk for SJS/TEN compared to non-carriers, and it is recommended that they receive an alternate drug. It is important to note that it is possible for a patient without HLA-B*15:02 to develop SJS/TEN. Guidelines regarding the use of pharmacogenomic tests in dosing for carbamazepine have been published in Clinical Pharmacology and Therapeutics by the Clinical Pharmacogenetics Implementation Consortium (CPIC) and are available on the PharmGKB website. [from PharmGKB]

Allopurinol is widely prescribed for the treatment of hyperuricemia and gout. An estimated 25-30% of gout patients in the UK and the US are treated with allopurinol. However, 0.1-0.4% of patients treated with allopurinol experience severe cutaneous adverse reactions (SCAR), including drug hypersensitivity syndrome, Stevens-Johnson syndrome, and toxic epidermal necrolysis. The genetic variant HLA-B*58:01, along with non-genetic factors, is known to be associated with this risk. Patients who are HLA-B*58:01-positive (having at least one copy of the HLA-B*58:01 allele) have a significantly increased risk of allopurinol-induced SCAR compared to those who are negative for this allele. It is still possible for a HLA-B*58:01 negative patient to develop SCAR on allopurinol. Guidelines regarding the use of pharmacogenomic tests in dosing for allopurinol have been published in Clinical Pharmacology and Therapeutics by the Clinical Pharmacogenetics Implementation Consortium (CPIC) and are available on the PharmGKB website. [from PharmGKB]

Carbamazepine is an aromatic anticonvulsant used to treat epilepsy and other seizure disorders, as well as bipolar disorder and trigeminal neuralgia. Carbamazepine can cause a variety of cutaneous adverse reactions, ranging from mild maculopapular eruptions to Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). The genetic variants HLA-B*15:02 and HLA-A*31:01 are associated with the risk of SJS/TEN. Patients who have at least one copy of the HLA-B*15:02 or HLA-A*31:01 allele (considered HLA-B*15:02 positive or HLA-A*31:01-positive, respectively) have a significantly increased risk for SJS/TEN compared to non-carriers, and it is recommended that they receive an alternate drug. It is important to note that it is possible for a patient without HLA-B*15:02 to develop SJS/TEN. Guidelines regarding the use of pharmacogenomic tests in dosing for carbamazepine have been published in Clinical Pharmacology and Therapeutics by the Clinical Pharmacogenetics Implementation Consortium (CPIC) and are available on the CPIC and PharmGKB websites. [from PharmGKB]

A rare autosomal recessive primary immunodeficiency characterized by absence of HLA class II molecules on the surface of immune cells, leading to severely impaired cellular and humoral immune response to foreign antigens, severe CD4+ T-cell lymphopenia, and hypogammaglobulinemia. The disease clinically manifests with early onset of severe and recurrent infections mainly of the respiratory and gastrointestinal tract, protracted diarrhea with failure to thrive, and autoimmune disease, and is frequently fatal in childhood. [from ORDO]

Celiac disease is a systemic autoimmune disease that can be associated with gastrointestinal findings (diarrhea, malabsorption, abdominal pain and distension, bloating, vomiting, and weight loss) and/or highly variable non-gastrointestinal findings (dermatitis herpetiformis, chronic fatigue, joint pain/inflammation, iron deficiency anemia, migraines, depression, attention-deficit disorder, epilepsy, osteoporosis/osteopenia, infertility and/or recurrent fetal loss, vitamin deficiencies, short stature, failure to thrive, delayed puberty, dental enamel defects, and autoimmune disorders). Classic celiac disease, characterized by mild to severe gastrointestinal symptoms, is less common than non-classic celiac disease, characterized by absence of gastrointestinal symptoms. [from GeneReviews]

Any sarcoidosis in which the cause of the disease is a mutation in the HLA-DRB1 gene. [from MONDO]

Malaria, a major cause of child mortality worldwide, is caused by mosquito-borne hematoprotozoan parasites of the genus Plasmodium. Of the 4 species that infect humans, P. falciparum causes the most severe forms of malaria and is the major cause of death and disease. Although less fatal, P. malariae, P. ovale, and, in particular, P. vivax infections are major causes of morbidity. The parasite cycle involves a first stage in liver cells and a subsequent stage at erythrocytes, when malaria symptoms occur. A wide spectrum of phenotypes are observed, from asymptomatic infection to mild disease, including fever and mild anemia, to severe disease, including cerebral malaria, profound anemia, and respiratory distress. Genetic factors influence the response to infection, as well as disease progression and severity. Malaria is the strongest known selective pressure in the recent history of the human genome, and it is the evolutionary driving force behind sickle-cell disease (603903), thalassemia (see 141800), glucose-6-phosphatase deficiency (300908), and other erythrocyte defects that together constitute the most common mendelian diseases of humans (Kwiatkowski, 2005; Campino et al., 2006). [from OMIM]

Bronchial asthma is the most common chronic disease affecting children and young adults. It is a complex genetic disorder with a heterogeneous phenotype, largely attributed to the interactions among many genes and between these genes and the environment. Asthma-related traits include clinical symptoms of asthma, such as coughing, wheezing, and dyspnea; bronchial hyperresponsiveness (BHR) as assessed by methacholine challenge test; serum IgE levels; atopy; and atopic dermatitis (Laitinen et al., 2001; Illig and Wjst, 2002; Pillai et al., 2006). See 147050 for information on the asthma-associated phenotype atopy. [from OMIM]

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disorder of the central nervous system (CNS) with various degrees of axonal damage. MS affects mainly young adults with predominance for females. The disorder often leads to substantial disability (summary by Bomprezzi et al., 2003). Genetic Heterogeneity of Susceptibility to Multiple Sclerosis Additional MS susceptibility loci include MS2 (612594) on chromosome 10p15, MS3 (612595) on chromosome 5p13, MS4 (612596) on chromosome 1p36, and MS5 (614810), conferred by variation in the TNFRSF1A gene (191190) on chromosome 12p13. [from OMIM]

Psoriasis (psoriasis vulgaris; PV) is a chronic inflammatory dermatosis that affects approximately 2% of the population. It is characterized by red, scaly skin patches that are usually found on the scalp, elbows, and knees, and may be associated with severe arthritis. The lesions are caused by abnormal keratinocyte proliferation and infiltration of inflammatory cells into the dermis and epidermis. The usual age of onset of psoriasis is between 15 and 30 years, although it can present at any age (summary by Matthews et al., 1996). Generalized pustular psoriasis (GPP) is a life-threatening disease characterized by sudden, repeated episodes of high-grade fever, generalized rash, and disseminated pustules, with hyperleukocytosis and elevated serum levels of C-reactive protein (123260) (summary by Marrakchi et al., 2011). GPP often presents in patients with existing or prior psoriasis vulgaris; however, GPP can develop without a history of PV (Sugiura et al., 2013). Palmoplantar pustulosis and acrodermatitis continua of Hallopeau represent acral forms of pustular psoriasis that have historically been grouped with GPP (summary by Setta-Kaffetzi et al., 2013). Nestle et al. (2009) provided a detailed review of the pathogenesis and genetics of psoriasis. Genetic Heterogeneity of Psoriasis and Psoriasis Susceptibility PSORS2 (602723) is caused by mutation in the CARD14 gene (607211) on chromosome 17q25, and PSORS14 (614204) is caused by mutation in the IL36RN gene (605507) on chromosome 2q14. Psoriasis susceptibility loci include PSORS1 on 6p21.3; PSORS3 (601454) on 4q; PSORS4 on 1q21; PSORS5 (604316) on 3q21; PSORS6 (605364) on 19p; PSORS7 (605606) on 1p; PSORS8 (610707) on 16q; PSORS9 (607857) on 4q31; PSORS10 (612410) on 18p11; PSORS11 (612599) on 5q31-q33; PSORS12 (612950) on 20q13; PSORS13 (614070), conferred by variation in the TRAF3IP2 gene (607043) on 6q21; and PSORS15 (616106), conferred by variation in the AP1S3 gene (615781) on 2q36. An additional putative psoriasis candidate locus has been reported on 20p (Nair et al., 1997). [from OMIM]

Tuberous sclerosis complex (TSC) involves abnormalities of the skin (hypomelanotic macules, confetti skin lesions, facial angiofibromas, shagreen patches, fibrous cephalic plaques, ungual fibromas); brain (subependymal nodules, cortical tubers, and subependymal giant cell astrocytomas [SEGAs], seizures, intellectual disability / developmental delay, psychiatric illness); kidney (angiomyolipomas, cysts, renal cell carcinomas); heart (rhabdomyomas, arrhythmias); and lungs (lymphangioleiomyomatosis [LAM], multifocal micronodular pneumonocyte hyperplasia). Central nervous system tumors are the leading cause of morbidity and mortality; renal disease is the second leading cause of early death. [from GeneReviews]

Bare lymphocyte syndrome type I (BLS I) is an inherited disorder of the immune system (primary immunodeficiency). Immunodeficiencies are conditions in which the immune system is not able to protect the body effectively from foreign invaders such as bacteria or viruses. Starting in childhood, most people with BLS I develop recurrent bacterial infections in the lungs and airways (respiratory tract). These recurrent infections can lead to a condition called bronchiectasis, which damages the passages leading from the windpipe to the lungs (bronchi) and can cause breathing problems.

Many people with BLS I also have open sores (ulcers) on their skin, usually on the face, arms, and legs. These ulcers typically develop in adolescence or young adulthood. Some people with BLS I have no symptoms of the condition.

People with BLS I have a shortage of specialized immune proteins called major histocompatibility complex (MHC) class I proteins on cells, including infection-fighting white blood cells (lymphocytes), which is where the condition got its name. [from MedlinePlus Genetics]

The pathogenesis of HIV infection and the progression from infection to AIDS vary significantly between exposed individuals. Infection occurs after the virus, which has macrophage (M)- and T lymphocyte (T)-tropic strains and more than 12 subtypes, survives an array of nonspecific, nongenetic environmental and host factors. [from OMIM]

Abacavir is a nucleoside reverse transcriptase inhibitor indicated for the treatment of HIV infection, in combination with other medications, as part of highly active antiretroviral therapy. Although abacavir is generally well tolerated, ~5–8% of patients experience a hypersensitivity reaction (HSR) during the first 6 weeks of treatment. Suspicion of an HSR requires immediate discontinuation of abacavir. Drug re-challenge is contraindicated because immediate life-threatening reactions can occur. HLA-B is a member of the major histocompatibility complex gene family and patients with at least one HLA-B*57:01 allele may develop HSR when treated with abacavir. HLA-B allele status has no effect on abacavir pharmacodynamics or pharmacokinetics; it only influences the likelihood that an HSR will occur. Guidelines regarding the use of pharmacogenomic tests in dosing for abacavir have been published in Clinical Pharmacology and Therapeutics by the Clinical Pharmacogenetics Implementation Consortium (CPIC) and are available on the PharmGKB website. [from PharmGKB]