MedGen

A rare, primary immunodeficiency with an autosomal dominant pattern of inheritance but incomplete penetrance. It is caused by a mutation in the FASLG (Fas ligand) gene that leads to defective Fas-induced apoptosis. Disruption of Fas-induced apoptosis impairs lymphocyte homeostasis and immune tolerance. Characteristic laboratory findings include an increase in circulating, double-negative (CD4-/CD8-) T cells in the setting of immune-mediated anemia, thrombocytopenia and neutropenia. Clinical signs present in childhood include fatigue, pallor, bruising, hepatosplenomegaly and chronic, non-malignant, non-infectious lymphadenopathy. The clinical course is influenced by a strong association with other autoimmune disorders and an increased risk for developing Hodgkin and non-Hodgkin lymphoma. [from NCI]

Autoimmune lymphoproliferative syndrome (ALPS), caused by defective lymphocyte homeostasis, is characterized by the following: Non-malignant lymphoproliferation (lymphadenopathy, hepatosplenomegaly with or without hypersplenism) that often improves with age. Autoimmune disease, mostly directed toward blood cells. Lifelong increased risk for both Hodgkin and non-Hodgkin lymphoma. In ALPS-FAS (the most common and best-characterized type of ALPS, associated with heterozygous germline pathogenic variants in FAS), non-malignant lymphoproliferation typically manifests in the first years of life, inexplicably waxes and wanes, and then often decreases without treatment in the second decade of life; in many affected individuals, however, neither splenomegaly nor the overall expansion of lymphocyte subsets in peripheral blood decreases. Although autoimmunity is often not present at the time of diagnosis or at the time of the most extensive lymphoproliferation, autoantibodies can be detected before autoimmune disease manifests clinically. In ALPS-FAS caused by homozygous or compound heterozygous (biallelic) pathogenic variants in FAS, severe lymphoproliferation occurs before, at, or shortly after birth, and usually results in death at an early age. ALPS-sFAS, resulting from somatic FAS pathogenic variants in selected cell populations, notably the alpha/beta double-negative T cells (a/ß-DNT cells), appears to be similar to ALPS-FAS resulting from heterozygous germline pathogenic variants in FAS, although lower incidence of splenectomy and lower lymphocyte counts have been reported in ALPS-sFAS and no cases of lymphoma have yet been published. [from GeneReviews]

Lung cancer is the leading cause of cancer deaths in the U.S. and worldwide. The 2 major forms of lung cancer are nonsmall cell lung cancer and small cell lung cancer (see 182280), which account for 85% and 15% of all lung cancers, respectively. Nonsmall cell lung cancer can be divided into 3 major histologic subtypes: squamous cell carcinoma, adenocarcinoma, and large cell lung cancer. Cigarette smoking causes all types of lung cancer, but it is most strongly linked with small cell lung cancer and squamous cell carcinoma. Adenocarcinoma is the most common type in patients who have never smoked. Nonsmall cell lung cancer is often diagnosed at an advanced stage and has a poor prognosis (summary by Herbst et al., 2008). [from OMIM]