MedGen

The phenotypic spectrum of ATP8B1 deficiency ranges from severe through moderate to mild. Severe ATP8B1 deficiency is characterized by infantile-onset cholestasis that progresses to cirrhosis, hepatic failure, and early death. Although mild-to-moderate ATP8B1 deficiency initially was thought to involve intermittent symptomatic cholestasis with a lack of hepatic fibrosis, it is now known that hepatic fibrosis may be present early in the disease course. Furthermore, in some persons with ATP8B1 deficiency the clinical findings can span the phenotypic spectrum, shifting over time from the mild end of the spectrum (episodic cholestasis) to the severe end of the spectrum (persistent cholestasis). Sensorineural hearing loss (SNHL) is common across the phenotypic spectrum. [from GeneReviews]

Erythropoietic protoporphyria (EPP) is characterized by cutaneous photosensitivity (usually beginning in infancy or childhood) that results in tingling, burning, pain, and itching within 30 minutes after exposure to sun or ultraviolet light and may be accompanied by swelling and redness. Symptoms (which may seem out of proportion to the visible skin lesions) may persist for hours or days after the initial phototoxic reaction. Photosensitivity remains for life. Multiple episodes of acute photosensitivity may lead to chronic changes of sun-exposed skin (lichenification, leathery pseudovesicles, grooving around the lips) and loss of lunulae of the nails. Approximately 20%-30% of individuals with EPP have some degree of liver dysfunction, which is typically mild with slight elevations of the liver enzymes. Up to 5% may develop more advanced liver disease which may be accompanied by motor neuropathy similar to that seen in the acute porphyrias. [from GeneReviews]

The phenotypic spectrum of ATP8B1 deficiency ranges from severe through moderate to mild. Severe ATP8B1 deficiency is characterized by infantile-onset cholestasis that progresses to cirrhosis, hepatic failure, and early death. Although mild-to-moderate ATP8B1 deficiency initially was thought to involve intermittent symptomatic cholestasis with a lack of hepatic fibrosis, it is now known that hepatic fibrosis may be present early in the disease course. Furthermore, in some persons with ATP8B1 deficiency the clinical findings can span the phenotypic spectrum, shifting over time from the mild end of the spectrum (episodic cholestasis) to the severe end of the spectrum (persistent cholestasis). Sensorineural hearing loss (SNHL) is common across the phenotypic spectrum. [from GeneReviews]

SCN9A neuropathic pain syndromes (SCN9A-NPS) comprise SCN9A erythromelalgia (EM), SCN9A paroxysmal extreme pain disorder (PEPD), and SCN9A small fiber neuropathy (SFN). SCN9A-EM is characterized by recurrent episodes of bilateral intense, burning pain, and redness, warmth, and occasionally swelling. While the feet are more commonly affected than the hands, in severely affected individuals the legs, arms, face, and/or ears may be involved. SCN9A-PEPD is characterized by neonatal or infantile onset of autonomic manifestations that can include skin flushing, harlequin (patchy or asymmetric) color change, tonic non-epileptic attacks (stiffening), and syncope with bradycardia. Later manifestations are episodes of excruciating deep burning rectal, ocular, or submandibular pain accompanied by flushing (erythematous skin changes). SCN9A-SFN is characterized by adult-onset neuropathic pain in a stocking and glove distribution, often with a burning quality; autonomic manifestations such as dry eyes, mouth, orthostatic dizziness, palpitations, bowel or bladder disturbances; and preservation of large nerve fiber functions (normal strength, tendon reflexes, and vibration sense). [from GeneReviews]

The phenotypic spectrum of ATP8B1 deficiency ranges from severe through moderate to mild. Severe ATP8B1 deficiency is characterized by infantile-onset cholestasis that progresses to cirrhosis, hepatic failure, and early death. Although mild-to-moderate ATP8B1 deficiency initially was thought to involve intermittent symptomatic cholestasis with a lack of hepatic fibrosis, it is now known that hepatic fibrosis may be present early in the disease course. Furthermore, in some persons with ATP8B1 deficiency the clinical findings can span the phenotypic spectrum, shifting over time from the mild end of the spectrum (episodic cholestasis) to the severe end of the spectrum (persistent cholestasis). Sensorineural hearing loss (SNHL) is common across the phenotypic spectrum. [from GeneReviews]

The signs and symptoms of PFIC2 are typically related to liver disease only; however, these signs and symptoms tend to be more severe than those experienced by people with PFIC1. People with PFIC2 often develop liver failure within the first few years of life. Additionally, affected individuals are at increased risk of developing a type of liver cancer called hepatocellular carcinoma.

In addition to signs and symptoms related to liver disease, people with PFIC1 may have short stature, deafness, diarrhea, inflammation of the pancreas (pancreatitis), and low levels of fat-soluble vitamins (vitamins A, D, E, and K) in the blood. Affected individuals typically develop liver failure before adulthood.

Most people with PFIC3 have signs and symptoms related to liver disease only. Signs and symptoms of PFIC3 usually do not appear until later in infancy or early childhood; rarely, people are diagnosed in early adulthood. Liver failure can occur in childhood or adulthood in people with PFIC3.

There are three known types of PFIC: PFIC1, PFIC2, and PFIC3. The types are also sometimes described as shortages of particular proteins needed for normal liver function. Each type has a different genetic cause.

Signs and symptoms of PFIC typically begin in infancy and are related to bile buildup and liver disease. Specifically, affected individuals experience severe itching, yellowing of the skin and whites of the eyes (jaundice), failure to gain weight and grow at the expected rate (failure to thrive), high blood pressure in the vein that supplies blood to the liver (portal hypertension), and an enlarged liver and spleen (hepatosplenomegaly).

Progressive familial intrahepatic cholestasis (PFIC) is a disorder that causes progressive liver disease, which typically leads to liver failure. In people with PFIC, liver cells are less able to secrete a digestive fluid called bile. The buildup of bile in liver cells causes liver disease in affected individuals. [from MedlinePlus Genetics]

Keratoderma with woolly hair is a group of related conditions that affect the skin and hair and in many cases increase the risk of potentially life-threatening heart problems. People with these conditions have hair that is unusually coarse, dry, fine, and tightly curled. In some cases, the hair is also sparse. The woolly hair texture typically affects only scalp hair and is present from birth. Starting early in life, affected individuals also develop palmoplantar keratoderma, a condition that causes skin on the palms of the hands and the soles of the feet to become thick, scaly, and calloused.

Cardiomyopathy, which is a disease of the heart muscle, is a life-threatening health problem that can develop in people with keratoderma with woolly hair. Unlike the other features of this condition, signs and symptoms of cardiomyopathy may not appear until adolescence or later. Complications of cardiomyopathy can include an abnormal heartbeat (arrhythmia), heart failure, and sudden death.

Keratoderma with woolly hair comprises several related conditions with overlapping signs and symptoms. Researchers have recently proposed classifying keratoderma with woolly hair into four types, based on the underlying genetic cause. Type I, also known as Naxos disease, is characterized by palmoplantar keratoderma, woolly hair, and a form of cardiomyopathy called arrhythmogenic right ventricular cardiomyopathy (ARVC). Type II, also known as Carvajal syndrome, has hair and skin abnormalities similar to type I but features a different form of cardiomyopathy, called dilated left ventricular cardiomyopathy. Type III also has signs and symptoms similar to those of type I, including ARVC, although the hair and skin abnormalities are often milder. Type IV is characterized by palmoplantar keratoderma and woolly and sparse hair, as well as abnormal fingernails and toenails. Type IV does not appear to cause cardiomyopathy. [from MedlinePlus Genetics]

The phenotypic spectrum of ATP8B1 deficiency ranges from severe through moderate to mild. Severe ATP8B1 deficiency is characterized by infantile-onset cholestasis that progresses to cirrhosis, hepatic failure, and early death. Although mild-to-moderate ATP8B1 deficiency initially was thought to involve intermittent symptomatic cholestasis with a lack of hepatic fibrosis, it is now known that hepatic fibrosis may be present early in the disease course. Furthermore, in some persons with ATP8B1 deficiency the clinical findings can span the phenotypic spectrum, shifting over time from the mild end of the spectrum (episodic cholestasis) to the severe end of the spectrum (persistent cholestasis). Sensorineural hearing loss (SNHL) is common across the phenotypic spectrum. [from GeneReviews]

Familial hypercholanemia-1 (FHCA1) is an autosomal recessive disorder characterized by elevated concentrations of bile acids (usually conjugated), itching, and fat malabsorption, leading to poor overall growth and deficiencies of fat-soluble vitamins. Vitamin D deficiency results in rickets, and vitamin K deficiency results in a coagulopathy (Morton et al., 2000; Shneider et al., 1997; summary by Carlton et al., 2003). See also bile acid conjugation defect-1 (BACD1; 619232), which can also show increased bile acid levels, although the bile acids in BACD1 are unconjugated. Genetic Heterogeneity of FHCA See FHCA2 (619256), caused by mutation in the SLC10A1 gene (182396) on chromosome 14q24. [from OMIM]

Darier-White disease (DAR), also known as keratosis follicularis, is an autosomal dominant skin disorder characterized by warty papules and plaques in seborrheic areas (central trunk, flexures, scalp, and forehead), palmoplantar pits, and distinctive nail abnormalities (Sakuntabhai et al., 1999). Onset is usually before the third decade, and penetrance is complete in adults, although expressivity is variable. Involvement may be severe, with widespread itchy malodorous crusted plaques, painful erosions, blistering, and mucosal lesions. Secondary infection is common. Sun, heat, and sweating exacerbate the symptoms. Darier disease never remits, but oral retinoids may reduce hyperkeratosis. Neuropsychiatric abnormalities, including mild mental retardation and epilepsy, have been described in association with Darier disease in a few families (Burge and Wilkinson, 1992); whether this is an association based on pleiotropism of the mutant gene or reflects coincidence is not clear. Histologic findings are (1) mild nonspecific perivascular infiltration in the dermis; (2) dermal villi protruding into the epidermis; (3) suprabasal detachment of the spinal layer leading to the formation of lacunae containing acantholytic cells; (4) in the more superficial epidermis, dyskeratotic round epidermal cells ('corps ronds'), the most distinctive feature; and (5) in the stratum corneum, 'grains' that resemble parakeratotic cells embedded in a hyperkeratotic horny layer. Electron microscopy reveals loss of desmosomal attachments, perinuclear aggregations of keratin filaments, and cytoplasmic vacuolization. Ultrastructural and immunologic studies suggest the disease results from an abnormality in the desmosome-keratin filament complex leading to a breakdown in cell adhesion. [from OMIM]

Dystrophic epidermolysis bullosa (DEB) is a genetic skin disorder affecting skin and nails that usually presents at birth. DEB is divided into two major types depending on inheritance pattern: recessive dystrophic epidermolysis bullosa (RDEB) and dominant dystrophic epidermolysis bullosa (DDEB). Each type is further divided into multiple clinical subtypes. Absence of a known family history of DEB does not preclude the diagnosis. Clinical findings in severe generalized RDEB include skin fragility manifest by blistering with minimal trauma that heals with milia and scarring. Blistering and erosions affecting the whole body may be present in the neonatal period. Oral involvement may lead to mouth blistering, fusion of the tongue to the floor of the mouth, and progressive diminution of the size of the oral cavity. Esophageal erosions can lead to webs and strictures that can cause severe dysphagia. Consequently, malnutrition and vitamin and mineral deficiency may lead to growth restriction in young children. Corneal erosions can lead to scarring and loss of vision. Blistering of the hands and feet followed by scarring fuses the digits into "mitten" hands and feet, with contractures and pseudosyndactyly. The lifetime risk of aggressive squamous cell carcinoma is higher than 90%. In contrast, the blistering in the less severe forms of RDEB may be localized to hands, feet, knees, and elbows with or without involvement of flexural areas and the trunk, and without the mutilating scarring seen in severe generalized RDEB. In DDEB, blistering is often mild and limited to hands, feet, knees, and elbows, but nonetheless heals with scarring. Dystrophic nails, especially toenails, are common and may be the only manifestation of DDEB. [from GeneReviews]

A group of rare autosomal recessive forms of ichthyosis with clinical characteristics of superficial, asymptomatic, spontaneous peeling of the skin and histologically by a shedding of the outer layers of the epidermis. Presents with either an acral or a generalised distribution. [from SNOMEDCT_US]

Intrahepatic cholestasis of pregnancy is a reversible form of cholestasis that occurs most often in the third trimester of pregnancy and recurs in 45 to 70% of subsequent pregnancies. Symptoms include pruritus, jaundice, increased serum bile salts, and abnormal liver enzymes, all of which resolve rapidly after delivery. However, the condition is associated with fetal complications, including placental insufficiency, premature labor, fetal distress, and intrauterine death. Women with ICP are also susceptible to oral contraceptive-induced cholestasis (OCIC). Ursodeoxycholic acid (UDCA) is an effective treatment for conditions caused by ABCB4 mutations (summary by Pasmant et al., 2012). Mutation in the ABCB4 gene accounts for about 15% of ICP cases (summary by Ziol et al., 2008). For a discussion of genetic heterogeneity of ICP, see ICP1 (147480). [from OMIM]

Autosomal recessive congenital ichthyosis (ARCI) encompasses several forms of nonsyndromic ichthyosis. Although most neonates with ARCI are collodion babies, the clinical presentation and severity of ARCI may vary significantly, ranging from harlequin ichthyosis, the most severe and often fatal form, to lamellar ichthyosis (LI) and (nonbullous) congenital ichthyosiform erythroderma (CIE). These phenotypes are now recognized to fall on a continuum; however, the phenotypic descriptions are clinically useful for clarification of prognosis and management. Infants with harlequin ichthyosis are usually born prematurely and are encased in thick, hard, armor-like plates of cornified skin that severely restrict movement. Life-threatening complications in the immediate postnatal period include respiratory distress, feeding problems, and systemic infection. Collodion babies are born with a taut, shiny, translucent or opaque membrane that encases the entire body and lasts for days to weeks. LI and CIE are seemingly distinct phenotypes: classic, severe LI with dark brown, plate-like scale with no erythroderma and CIE with finer whiter scale and underlying generalized redness of the skin. Affected individuals with severe involvement can have ectropion, eclabium, scarring alopecia involving the scalp and eyebrows, and palmar and plantar keratoderma. Besides these major forms of nonsyndromic ichthyosis, a few rare subtypes have been recognized, such as bathing suit ichthyosis, self-improving collodion ichthyosis, or ichthyosis-prematurity syndrome. [from GeneReviews]

Arthrogryposis, renal dysfunction, and cholestasis-2 (ARCS2) is a multisystem disorder associated with abnormalities in polarized liver and kidney cells (Qiu et al., 2019). For a general phenotypic description and a discussion of genetic heterogeneity of ARCS, see ARCS1 (208085). [from OMIM]

Familial cold autoinflammatory syndrome-3 is an autosomal dominant immune disorder characterized by the development of cutaneous urticaria, erythema, and pruritus in response to cold exposure. Affected individuals have variable additional immunologic defects, including antibody deficiency, decreased numbers of B cells, defective B cells, increased susceptibility to infection, and increased risk of autoimmune disorders (summary by Ombrello et al., 2012). For a discussion of genetic heterogeneity of FCAS, see FCAS1 (120100). [from OMIM]

Intrahepatic cholestasis of pregnancy is a reversible form of cholestasis that occurs most often in the third trimester of pregnancy and recurs in 45 to 70% of subsequent pregnancies. Symptoms include pruritus, jaundice, increased serum bile salts, and abnormal liver enzymes, all of which resolve rapidly after delivery. However, the condition is associated with fetal complications, including placental insufficiency, premature labor, fetal distress, and intrauterine death. Some women with ICP may also be susceptible to oral contraceptive-induced cholestasis (OCIC) (summary by Pasmant et al., 2012). Genetic Heterogeneity of Intrahepatic Cholestasis of Pregnancy See also ICP3 (614972), caused by mutation in the ABCB4 gene (171060). [from OMIM]

Hypotrichosis-6 (HYPT6) is a localized autosomal recessive hypotrichosis characterized by fragile hairs that break easily, leaving short, sparse scalp hairs. The disorder affects the trunk and extremities as well as the scalp, and the eyebrows and eyelashes may also be involved, whereas beard, pubic, and axillary hairs are largely spared. In addition, patients can develop hyperkeratotic follicular papules, erythema, and pruritus in affected areas. In some patients with congenital hypotrichosis, monilethrix-like hairs showing elliptical nodes have been observed (summary by Schaffer et al., 2006). Genetic Heterogeneity of Autosomal Recessive Localized Hypotrichosis LAH2 (HYPT7; 604379) is caused by mutation in the LIPH gene (607365) on chromosome 3q27, and LAH3 (HYPT8; 278150) is caused by mutation in the LPAR6 (P2RY5) gene (609239) on chromosome 13q14.12-q14.2. See also hypotrichosis and recurrent skin vesicles (613102), which is caused by mutation in the DSC3 gene (600271). [from OMIM]

Familial erythrocytosis-4 (ECYT4) is an autosomal dominant disorder characterized by increased serum red blood cell mass and hemoglobin concentration as well as elevated serum erythropoietin (EPO; 133170). For a general phenotypic description and a discussion of genetic heterogeneity of familial erythrocytosis, see ECYT1 (133100). [from OMIM]

PDGFRA-associated chronic eosinophilic leukemia is a form of blood cell cancer characterized by an elevated number of cells called eosinophils in the blood. These cells help fight infections by certain parasites and are involved in the inflammation associated with allergic reactions. However, these circumstances do not account for the increased number of eosinophils in PDGFRA-associated chronic eosinophilic leukemia.

Another characteristic feature of PDGFRA-associated chronic eosinophilic leukemia is organ damage caused by the excess eosinophils. Eosinophils release substances to aid in the immune response, but the release of excessive amounts of these substances causes damage to one or more organs, most commonly the heart, skin, lungs, or nervous system. Eosinophil-associated organ damage can lead to a heart condition known as eosinophilic endomyocardial disease, skin rashes, coughing, difficulty breathing, swelling (edema) in the lower limbs, confusion, changes in behavior, or impaired movement or sensations. People with PDGFRA-associated chronic eosinophilic leukemia can also have an enlarged spleen (splenomegaly) and elevated levels of certain chemicals called vitamin B12 and tryptase in the blood.

Some people with PDGFRA-associated chronic eosinophilic leukemia have an increased number of other types of white blood cells, such as neutrophils or mast cells. Occasionally, people with PDGFRA-associated chronic eosinophilic leukemia develop other blood cell cancers, such as acute myeloid leukemia or B-cell or T-cell acute lymphoblastic leukemia or lymphoblastic lymphoma.

PDGFRA-associated chronic eosinophilic leukemia is often grouped with a related condition called hypereosinophilic syndrome. These two conditions have very similar signs and symptoms; however, the cause of hypereosinophilic syndrome is unknown. [from MedlinePlus Genetics]