Complement hyperactivation, angiopathic thrombosis, and protein-losing enteropathy (CHAPLE) is characterized by abdominal pain and diarrhea, primary intestinal lymphangiectasia, hypoproteinemic edema, and malabsorption. Some patients also exhibit bowel inflammation, recurrent infections associated with hypogammaglobulinemia, and/or angiopathic thromboembolic disease. Patient T lymphocytes show increased complement activation, causing surface deposition of complement and generating soluble C5a (Ozen et al., 2017).

Johanson-Blizzard syndrome is an autosomal recessive disorder characterized by poor growth, mental retardation, and variable dysmorphic features, including aplasia or hypoplasia of the nasal alae, abnormal hair patterns or scalp defects, and oligodontia. Other features include hypothyroidism, sensorineural hearing loss, imperforate anus, and pancreatic exocrine insufficiency (summary by Al-Dosari et al., 2008).

A form of congenital disorders of N-linked glycosylation characterized by generalized hypotonia, craniofacial dysmorphism (prominent occiput, short palpebral fissures, long eyelashes, broad nose, high arched palate, retrognathia), hypoplastic genitalia, seizures, feeding difficulties, hypoventilation, severe hypogammaglobulinemia with generalized edema and increased resistance to particular viral infections (particularly to enveloped viruses). The disease is caused by loss-of-function mutations in the gene MOGS (2p13.1).

An extremely rare association syndrome, described in only two brothers to date (one of which died at 2 months of age), characterized by aplasia cutis congenita of the vertex and generalized edema (as well as hypoproteinemia and lymphopenia) due to intestinal lymphangiectasia. There have been no further descriptions in the literature since 1985.

Familial hemophagocytic lymphohistiocytosis-2 (FHL2) is an autosomal recessive disorder of immune dysregulation with onset in infancy or early childhood. It is characterized clinically by fever, edema, hepatosplenomegaly, and liver dysfunction. Neurologic impairment, seizures, and ataxia are frequent. Laboratory studies show pancytopenia, coagulation abnormalities, hypofibrinogenemia, and hypertriglyceridemia. There is increased production of cytokines, such as gamma-interferon (IFNG; 147570) and TNF-alpha (191160), by hyperactivation and proliferation of T cells and macrophages. Activity of cytotoxic T cells and NK cells is reduced, consistent with a defect in cellular cytotoxicity. Bone marrow, lymph nodes, spleen, and liver show features of hemophagocytosis. Chemotherapy and/or immunosuppressant therapy may result in symptomatic remission, but the disorder is fatal without bone marrow transplantation (summary by Dufourcq-Lagelouse et al., 1999, Stepp et al., 1999, and Molleran Lee et al., 2004). For a general phenotypic description and a discussion of genetic heterogeneity of FHL, see 267700.

Any nephrotic syndrome in which the cause of the disease is a mutation in the ARHGDIA gene.

Lymphatic malformation-6 is a form of generalized lymphatic dysplasia (GLD), which is characterized by a uniform, widespread lymphedema affecting all segments of the body, with systemic involvement such as intestinal and/or pulmonary lymphangiectasia, pleural effusions, chylothoraces and/or pericardial effusions. In LMPHM6, there is a high incidence of nonimmune hydrops fetalis (NIHF) with either death or complete resolution of the neonatal edema, but childhood onset of lymphedema with or without systemic involvement also occurs. Mild facial edema is often present. Patients have normal intelligence and no seizures (summary by Fotiou et al., 2015). For a discussion of genetic heterogeneity of lymphatic malformation, see 153100.

Any Neu-Laxova syndrome in which the cause of the disease is a mutation in the PHGDH gene.

Familial Hemophagocytic lymphohistiocytosis (FHL) is a rare primary immunodeficiency characterized by a macrophage activation syndrome with an onset usually occurring within a few months or less common several years after birth.

The fetal akinesia deformation sequence (FADS) refers to a clinically and genetically heterogeneous constellation of features including fetal akinesia, intrauterine growth retardation, arthrogryposis, and developmental anomalies, including lung hypoplasia, cleft palate, and cryptorchidism (Vogt et al., 2009). It shows phenotypic overlap with the lethal form of multiple pterygium syndrome (see 253290). For a general phenotypic description and a discussion of genetic heterogeneity of FADS, see 208150.

Lymphatic malformation-8 (LMPHM8) is an autosomal recessive disorder in which affected fetuses die in utero due to nonimmune hydrops fetalis (NIHF). The fetus and placenta are edematous with interstitial accumulation of fluid and abnormally shaped vessels. The disorder results from impaired lymphangiogenesis. Carrier females have reduced fertility and recurrent miscarriages likely due to NIHF (summary by Mackie et al., 2018). For a discussion of genetic heterogeneity of lymphatic malformation, see LMPHM1 (153100).

Nephrotic syndrome type 22 (NPHS22) is an autosomal recessive renal disease characterized by onset of progressive kidney dysfunction in infancy. Affected individuals usually present with edema associated with hypoproteinemia, proteinuria, and microscopic hematuria. Renal biopsy shows effacement of the podocyte foot processes, glomerulosclerosis, and thickening of the glomerular basement membrane. The disease is steroid-resistant and progressive, resulting in end-stage renal disease usually necessitating kidney transplant (Majmundar et al., 2021). For a general phenotypic description and a discussion of genetic heterogeneity of nephrotic syndrome, see NPHS1 (256300).

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is a severe disorder affecting the muscles that line the bladder and intestines. It is characterized by impairment of the muscle contractions that move food through the digestive tract (peristalsis) and empty the bladder.\n\nSome of the major features of MMIHS can be recognized before birth using ultrasound imaging. Affected fetuses have an enlarged bladder (megacystis) because it does not empty. In addition, the large intestine (colon) is abnormally narrow (microcolon) because of a shortage of functional muscle lining it. Intestinal and bladder problems persist throughout life.\n\nAfter birth, the continued impairment of peristalsis (hypoperistalsis) often causes a digestive condition called intestinal pseudo-obstruction. This condition, which mimics a physical blockage (obstruction) of the intestines but without an actual blockage, leads to a buildup of partially digested food in the intestines. This buildup can cause abdominal swelling (distention) and pain, nausea, and vomiting. The vomit usually contains a green or yellow digestive fluid called bile. Because digestion is impeded and the body does not get the nutrients from food, nutritional support is usually needed, which is given through intravenous feedings (parenteral nutrition). While some affected individuals rely solely on intravenous feedings, others require it only on occasion. Long-term use of parenteral nutrition can lead to liver problems.\n\nThe reduced ability to pass urine also contributes to painful distention of the abdomen. Many people with MMIHS require placement of a tube (urinary catheter) to remove urine from the bladder.\n\nAnother abnormality in some people with MMIHS is intestinal malrotation, in which the intestines do not fold properly. Instead, they twist abnormally, often causing a blockage. Individuals with MMIHS can also develop problems with the kidneys or the ureters, which are the ducts that carry urine from the kidneys to the bladder.\n\nThe life expectancy of people with MMIHS is shorter than normal, often due to malnutrition, overwhelming infection (sepsis), or the failure of multiple organs.

Biliary, renal, neurologic, and skeletal syndrome (BRENS) is an autosomal recessive complex ciliopathy with multisystemic manifestations. The most common presentation is severe neonatal cholestasis that progresses to liver fibrosis and cirrhosis. Most patients have additional clinical features suggestive of a ciliopathy, including postaxial polydactyly, hydrocephalus, retinal abnormalities, and situs inversus. Additional features of the syndrome may include congenital cardiac defects, echogenic kidneys with renal failure, ocular abnormalities, joint hyperextensibility, and dysmorphic facial features. Some patients have global developmental delay. Brain imaging typically shows dilated ventricles, hypomyelination, and white matter abnormalities, although some patients have been described with abnormal pituitary development (summary by Shaheen et al., 2020 and David et al., 2020).