Melkersson-Rosenthal syndrome is characterized by chronic swelling of the face, peripheral facial palsy, which may be bilateral and may tend to relapse, and in some cases ligua plicata (fissured tongue). The swelling is localized especially to the lips. Onset is usually in childhood or adolescence (summary by Kunstadter, 1965).

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is an uncommon form of T-cell non-Hodgkin lymphoma in which cytotoxic CD8 (see 186910)+ T cells infiltrate adipose tissue forming subcutaneous nodules. Both children and adults can be affected, with a median age at diagnosis of 36 years and a female gender bias. Most patients have accompanying systemic features such as fever or flank pain. A subset (about 20%) of patients develop hemophagocytic lymphohistiocytosis (HLH), usually associated with CD8+ T cells rimming adipocytes in the bone marrow. An infectious agent is not identified, and the disorder is believed to result from improperly activated inflammation. Immunosuppressive therapy may be helpful; hematopoietic bone marrow transplantation is usually curative (summary by Gayden et al., 2018). For a general discussion of genetic heterogeneity of HLH, see HLH1 (267700).

An extremely rare multi-systemic genetic disorder with characteristics of intellectual disability, deafness, skeletal abnormalities and coarse facial features.The syndrome is exceedingly rare and has been reported in only a few patients to date. Male and female patients have been described. The main clinical features include moderate to severe intellectual deficit, congenital sensorineural hearing impairment and broad, stubby hands and feet. A coarse face with full lips and cheeks is also found. These signs are reported to become more prominent with age. The pattern of inheritance appears to be autosomal recessive.

Pulmonary lymphangiectasia is a rare congenital vascular dysplasia characterized by an increased number of dilated pulmonary lymphatics in the subpleural, peribronchial, and interlobular septa. Respiratory distress is usually noted immediately after birth (summary by Stevenson et al., 2006).

Hereditary angioedema is a disorder characterized by recurrent episodes of severe swelling (angioedema). The parts of the body that are most often affected by swelling are the limbs, face, intestinal tract, and airway. Minor trauma or stress may trigger an attack, but swelling often occurs without a known trigger. Episodes involving the intestinal tract cause severe abdominal pain, nausea, and vomiting. Swelling in the airway can restrict breathing and lead to life-threatening obstruction of the airway. About one-third of people with this condition develop a non-itchy rash called erythema marginatum during an attack.\n\nSymptoms of hereditary angioedema typically begin in childhood and worsen during puberty.  On average, untreated individuals have swelling episodes every 1 to 2 weeks, and most episodes last for about 3 to 4 days. The frequency and duration of attacks vary greatly among people with hereditary angioedema, even among people in the same family.\n\nHereditary angioedema is broadly divided into two types, which are distinguished by levels of a protein called C1 inhibitor (C1-INH) in the blood. These types are known as hereditary angioedema due to C1-INH deficiency and hereditary angioedema with normal C1-INH. \n\n\n\nHereditary angioedema due to C1-INH deficiency is further divided into two types: type I occurs when C1-INH levels are low, and type II occurs when the C1-INH protein is not functioning correctly. \n\nThe different types of hereditary angioedema have similar signs and symptoms. 

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.

Sialidosis is an autosomal recessive disorder characterized by the progressive lysosomal storage of sialylated glycopeptides and oligosaccharides caused by a deficiency of the enzyme neuraminidase. Common to the sialidoses is the accumulation and/or excretion of sialic acid (N-acetylneuraminic acid) covalently linked ('bound') to a variety of oligosaccharides and/or glycoproteins (summary by Lowden and O'Brien, 1979). The sialidoses are distinct from the sialurias in which there is storage and excretion of 'free' sialic acid, rather than 'bound' sialic acid; neuraminidase activity in sialuria is normal or elevated. Salla disease (604369) is a form of 'free' sialic acid disease. Classification Lowden and O'Brien (1979) provided a logical nosology of neuraminidase deficiency into sialidosis type I and type II. Type I is the milder form, also known as the 'normosomatic' type or the cherry red spot-myoclonus syndrome. Sialidosis type II is the more severe form with an earlier onset, and is also known as the 'dysmorphic' type. Type II has been subdivided into juvenile and infantile forms. Other terms for sialidosis type II are mucolipidosis I and lipomucopolysaccharidosis.

LMPHM7 is an autosomal dominant disorder with variable expressivity. Some patients may develop severe nonimmune lymphatic-related hydrops fetalis (LRHF) in utero, resulting in early death, whereas others may have milder manifestations, such as atrial septal defect (ASD) or varicose veins as adults. The hydrops and/or swelling improves spontaneously in those who survive the neonatal period (summary by Martin-Almedina et al., 2016). For a discussion of genetic heterogeneity of lymphatic malformation, see 153100.

Primary lymphedema is caused by anatomic or functional defects in the lymphatic system, resulting in chronic swelling of body parts. There may be accompanying nail and skin changes, such as nail dysplasia or papillomatosis. Onset is usually at birth or in early childhood but can occur later, and the severity is variable (summary by Gordon et al., 2013 and Balboa-Beltran et al., 2014). For a discussion of the genetic heterogeneity of lymphocytic malformation, see 153100.

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.

Hereditary angioedema-5 (HAE5) is an autosomal dominant disorder characterized by localized and self-limiting edema of the subcutaneous or submucosal tissue due to an episodic increase in vascular permeability. Affected individuals have onset of episodic swelling of the face, lips, hands, and abdomen in the second decade of life. Treatment with tranexamic acid may be effective in reducing the severity and frequency of the attacks (summary by Bafunno et al., 2018). For a discussion of genetic heterogeneity of hereditary angioedema, see 106100.

Hereditary angioedema-6 (HAE6) is an autosomal dominant disorder characterized by onset of episodic subcutaneous and submucosal swelling in adulthood. The face, mouth, and tongue are often affected; some patients have distal limb or abdominal edema. Levels of complement component inhibitor (C1INH; 606860) are normal (summary by Bork et al., 2019). For a discussion of genetic heterogeneity of HAE, see 106100.

Hereditary angioedema-7 (HAE7) is an autosomal dominant disorder characterized by onset of recurrent episodic swelling of the face, lips, and oral mucosa in the second decade. The disorder is due to abnormal vascular permeability (summary by Ariano et al., 2020). For a discussion of genetic heterogeneity of HAE, see 106100.

Hereditary angioedema-8 (HAE8) is an autosomal dominant disorder characterized clinically by recurrent and self-limited episodes of localized edema in various organs, including the face, tongue, larynx, and extremities. In rare cases, swelling of the tongue or larynx can lead to airway obstruction. Abdominal attacks may also occur, resulting in abdominal pain, vomiting, and diarrhea. The disorder results from enhanced vascular permeability (summary by Bork et al., 2021). For a discussion of genetic heterogeneity of HAE, see 106100.