MedGen

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]

Epidermolysis bullosa simplex (EBS) is characterized by fragility of the skin (and mucosal epithelia in some instances) that results in non-scarring blisters and erosions caused by minor mechanical trauma. EBS is distinguished from other types of epidermolysis bullosa (EB) or non-EB skin fragility syndromes by the location of the blistering in relation to the dermal-epidermal junction. In EBS, blistering occurs within basal keratinocytes. The severity of blistering ranges from limited to hands and feet to widespread involvement. Additional features can include hyperkeratosis of the palms and soles (keratoderma), nail dystrophy, milia, and hyper- and/or hypopigmentation. Rare EBS subtypes have been associated with additional clinical features including pyloric atresia, muscular dystrophy, cardiomyopathy, and/or nephropathy. [from GeneReviews]

Hidrotic ectodermal dysplasia 2, or Clouston syndrome (referred to as HED2 throughout this GeneReview) is characterized by a triad of major clinical features including partial-to-complete alopecia, nail dystrophy, and palmoplantar hyperkeratosis. Sweating is preserved and there are usually no dental anomalies. Sparse scalp hair and dysplastic nails are seen early in life. In infancy, scalp hair is fine, sparse, and brittle. Progressive hair loss may lead to total alopecia by puberty. The nails may be milky white in early childhood; they gradually become dystrophic, thick, and distally separated from the nail bed. Palmoplantar keratoderma may develop during childhood and increases in severity with age. Associated features may include cutaneous hyperpigmentation (particularly over the joints) and finger clubbing. The clinical manifestations are highly variable even within the same family. [from GeneReviews]

Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF. [from GeneReviews]

Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF. [from GeneReviews]

Epidermolysis bullosa simplex (EBS) is characterized by fragility of the skin (and mucosal epithelia in some instances) that results in non-scarring blisters and erosions caused by minor mechanical trauma. EBS is distinguished from other types of epidermolysis bullosa (EB) or non-EB skin fragility syndromes by the location of the blistering in relation to the dermal-epidermal junction. In EBS, blistering occurs within basal keratinocytes. The severity of blistering ranges from limited to hands and feet to widespread involvement. Additional features can include hyperkeratosis of the palms and soles (keratoderma), nail dystrophy, milia, and hyper- and/or hypopigmentation. Rare EBS subtypes have been associated with additional clinical features including pyloric atresia, muscular dystrophy, cardiomyopathy, and/or nephropathy. [from GeneReviews]

Epidermolysis bullosa simplex (EBS) is characterized by fragility of the skin (and mucosal epithelia in some instances) that results in non-scarring blisters and erosions caused by minor mechanical trauma. EBS is distinguished from other types of epidermolysis bullosa (EB) or non-EB skin fragility syndromes by the location of the blistering in relation to the dermal-epidermal junction. In EBS, blistering occurs within basal keratinocytes. The severity of blistering ranges from limited to hands and feet to widespread involvement. Additional features can include hyperkeratosis of the palms and soles (keratoderma), nail dystrophy, milia, and hyper- and/or hypopigmentation. Rare EBS subtypes have been associated with additional clinical features including pyloric atresia, muscular dystrophy, cardiomyopathy, and/or nephropathy. [from GeneReviews]

Epidermolytic palmoplantar keratoderma-1 (EPPK1) is an autosomal dominant skin disorder characterized clinically by diffuse, yellow thickening of the skin of the palms and soles. There is no extension of the keratoderma to dorsal surfaces of hands and feet, inner wrists, and Achilles tendon area (transgrediens). Knuckle pads may be present in some individuals (summary by Kuster et al., 2002, Chiu et al., 2007). Genetic Heterogeneity of Epidermolytic Palmoplantar Keratoderma Epidermolytic palmoplantar keratoderma-2 (EPPK2; 620411) is caused by mutation in the keratin-1 gene (KRT1; 139350) on chromosome 12q13. Classification of Palmoplantar Keratoderma PPK has been classified into diffuse, focal, and punctate forms according to the pattern of hyperkeratosis on the palms and soles (Lucker et al., 1994). Diffuse PPK develops at birth or shortly thereafter and involves the entire palm and sole with a sharp cutoff at an erythematous border; there are no lesions outside the volar skin, and, in particular, no follicular or oral lesions. In contrast, focal PPK is a late-onset form in which focal hyperkeratotic lesions develop in response to mechanical trauma; an important distinguishing feature is the presence of lesions at other body sites, e.g., oral and follicular hyperkeratosis (Stevens et al., 1996). Palmoplantar keratodermas can be further subdivided histologically into epidermolytic and nonepidermolytic PPK (Risk et al., 1994). Genetic Heterogeneity of Palmoplantar Keratoderma Nonepidermolytic palmoplantar keratoderma (NEPPK; 600962) is caused by mutation in the KRT1 gene. A focal form of NEPPK (FNEPPK1; 613000) is caused by mutation in the KRT16 gene (148067). Another focal form, FNEPPK2 (616400), is caused by mutation in the TRPV3 gene (607066); mutation in TRPV3 can also cause Olmsted syndrome (OLMS; 614594), a severe mutilating form of PPK. The diffuse Bothnian form of NEPPK (PPKB; 600231) is caused by mutation in the AQP5 gene (600442). The Nagashima type of nonepidermolytic diffuse PPK (PPKN; 615598) is caused by mutation in the SERPINB7 gene (603357). A generalized form of epidermolytic hyperkeratosis (EHK; 113800), also designated bullous congenital ichthyosiform erythroderma (BCIE), is caused by mutation in the keratin genes KRT1 and KRT10 (148080). For a discussion of punctate PPK, see 148600; for a discussion of striate PPK, see 148700. [from OMIM]

Cardiofaciocutaneous (CFC) syndrome is characterized by cardiac abnormalities (pulmonic stenosis and other valve dysplasias, septal defects, hypertrophic cardiomyopathy, rhythm disturbances), distinctive craniofacial appearance, and cutaneous abnormalities (including xerosis, hyperkeratosis, ichthyosis, keratosis pilaris, ulerythema ophryogenes, eczema, pigmented moles, hemangiomas, and palmoplantar hyperkeratosis). The hair is typically sparse, curly, fine or thick, woolly or brittle; eyelashes and eyebrows may be absent or sparse. Nails may be dystrophic or fast growing. Some form of neurologic and/or cognitive delay (ranging from mild to severe) is seen in all affected individuals. Neoplasia, mostly acute lymphoblastic leukemia, has been reported in some individuals. [from GeneReviews]

Dilated cardiomyopathy with woolly hair and keratoderma (DCWHK) is characterized by the presence of woolly or sparse hair from birth. Some patients exhibit fragile skin with blisters/erosions after minor mechanical trauma, with hyperkeratosis and epidermolytic keratoderma developing in early childhood. Cardiomyopathy may become apparent in the first decade of life, and early death due to heart failure has been reported, but patients may remain asymptomatic into the fourth decade of life. Some patients exhibit an arrhythmogenic form of cardiomyopathy, with sudden death in early adulthood (Carvajal-Huerta, 1998; Whittock et al., 2002; Alcalai et al., 2003; Uzumcu et al., 2006). Another syndrome involving cardiomyopathy, woolly hair, and keratoderma (Naxos disease; 601214) is caused by mutation in the plakoglobin gene (JUP; 173325). Also see 610476 for a similar disorder caused by homozygous mutation in the DSC2 gene (125645). Dilated cardiomyopathy with woolly hair, keratoderma, and tooth agenesis (DCWHKTA; 615821) is caused by heterozygous mutation in DSP. An isolated form of striated PPK (PPKS2; 612908) is also caused by heterozygous mutation in DSP. Reviews In a review of cardiocutaneous syndromes and arrhythmogenic cardiomyopathy, Sen-Chowdhry and McKenna (2014) stated that although the cardiac component of Carvajal syndrome was originally considered dilated cardiomyopathy, many of its features resemble those of arrhythmogenic cardiomyopathy (see 607450). In addition, they noted that different disease subtypes have been found to coexist within the same kindred, suggesting a role for modifier genes and/or environmental influences. [from OMIM]

Pachyonychia congenita (PC) is characterized by hypertrophic nail dystrophy, painful palmoplantar keratoderma and blistering, oral leukokeratosis, pilosebaceous cysts (including steatocystoma and vellus hair cysts), palmoplantar hyperhydrosis, and follicular keratoses on the trunk and extremities. [from GeneReviews]

Palmoplantar keratoderma with deafness is a disorder characterized by skin abnormalities and hearing loss. Affected individuals develop unusually thick skin on the palms of the hands and soles of the feet (palmoplantar keratoderma) beginning in childhood. Hearing loss ranges from mild to profound. It begins in early childhood and gets worse over time. Affected individuals have particular trouble hearing high-pitched sounds.

The signs and symptoms of this disorder may vary even within the same family, with some individuals developing only skin abnormalities and others developing only hearing loss. [from MedlinePlus Genetics]

Triple A syndrome is an inherited condition characterized by three specific features: achalasia, Addison disease, and alacrima. Achalasia is a disorder that affects the ability to move food through the esophagus, the tube that carries food from the throat to the stomach. It can lead to severe feeding difficulties and low blood glucose (hypoglycemia). Addison disease, also known as primary adrenal insufficiency, is caused by abnormal function of the small hormone-producing glands on top of each kidney (adrenal glands). The main features of Addison disease include fatigue, loss of appetite, weight loss, low blood pressure, and darkening of the skin. The third major feature of triple A syndrome is a reduced or absent ability to secrete tears (alacrima). Most people with triple A syndrome have all three of these features, although some have only two.

Many of the features of triple A syndrome are caused by dysfunction of the autonomic nervous system. This part of the nervous system controls involuntary body processes such as digestion, blood pressure, and body temperature. People with triple A syndrome often experience abnormal sweating, difficulty regulating blood pressure, unequal pupil size (anisocoria), and other signs and symptoms of autonomic nervous system dysfunction (dysautonomia).

People with this condition may have other neurological abnormalities, such as developmental delay, intellectual disability, speech problems (dysarthria), and a small head size (microcephaly). In addition, affected individuals commonly experience muscle weakness, movement problems, and nerve abnormalities in their extremities (peripheral neuropathy). Some develop optic atrophy, which is the degeneration (atrophy) of the nerves that carry information from the eyes to the brain. Many of the neurological symptoms of triple A syndrome worsen over time.

People with triple A syndrome frequently develop a thickening of the outer layer of skin (hyperkeratosis) on the palms of their hands and the soles of their feet. Other skin abnormalities may also be present in people with this condition.

Alacrima is usually the first noticeable sign of triple A syndrome, as it becomes apparent early in life that affected children produce little or no tears while crying. They develop Addison disease and achalasia during childhood or adolescence, and most of the neurologic features of triple A syndrome begin during adulthood. The signs and symptoms of this condition vary among affected individuals, even among members of the same family. [from MedlinePlus Genetics]

Aggressive periodontitis, which may be generalized or localized, is characterized by severe and protracted gingival infections, leading to tooth loss. Amounts of microbial deposits are generally inconsistent with the severity of periodontal tissue destruction and the progression of attachment and bone loss may be self arresting (American Academy of Periodontology, 2000). The term 'aggressive periodontitis' replaced the terms 'early-onset,' 'prepubertal,' or 'juvenile periodontitis' at a 1999 International workshop for a classification of periodontal disease and conditions, where it was decided that the classification terminology should not be age dependent or require knowledge of rates of progression (Armitage, 1999). Genetic Heterogeneity of Aggressive Periodontitis Aggressive periodontitis-2 (608526) has been mapped to chromosome 1q25. [from OMIM]

Hystrix-like ichthyosis with deafness (HID) is a disorder characterized by dry, scaly skin (ichthyosis) and hearing loss that is usually profound. Hystrix-like means resembling a porcupine; in this type of ichthyosis, the scales may be thick and spiky, giving the appearance of porcupine quills.

Newborns with HID typically develop reddened skin. The skin abnormalities worsen over time, and the ichthyosis eventually covers most of the body, although the palms of the hands and soles of the feet are usually only mildly affected. Breaks in the skin may occur and in severe cases can lead to life-threatening infections. Affected individuals have an increased risk of developing a type of skin cancer called squamous cell carcinoma, which can also affect mucous membranes such as the inner lining of the mouth. People with HID may also have patchy hair loss caused by scarring on particular areas of skin. [from MedlinePlus Genetics]

Papillion-Lefevre syndrome (PALS) is an autosomal recessive disorder characterized by palmoplantar keratoderma, periodontitis, and premature loss of dentition (summary by Lefevre et al., 2001). [from OMIM]

Kindler syndrome (KS), a rare subtype of inherited epidermolysis bullosa, is characterized by skin fragility and acral blister formation beginning at birth, diffuse cutaneous atrophy, photosensitivity (most prominent during childhood and usually decreasing after adolescence), poikiloderma, diffuse palmoplantar hyperkeratosis, and pseudosyndactyly. Mucosal manifestations are also common and include hemorrhagic mucositis and gingivitis, periodontal disease, premature loss of teeth, and labial leukokeratosis. Other mucosal findings can include ectropion, urethral stenosis, and severe phimosis. Severe long-term complications of KS include periodontitis, mucosal strictures, and aggressive squamous cell carcinomas. Manifestations can range from mild to severe. [from GeneReviews]

Yunis-Varon syndrome (YVS) is a severe autosomal recessive disorder characterized by skeletal defects, including cleidocranial dysplasia and digital anomalies, and severe neurologic involvement with neuronal loss. Enlarged cytoplasmic vacuoles are found in neurons, muscle, and cartilage. The disorder is usually lethal in infancy (summary by Campeau et al., 2013). [from OMIM]

Woolly hair (WH) refers to a group of hair shaft disorders that are characterized by fine and tightly curled hair. Compared to normal curly hair that is observed in some populations, WH grows slowly and stops growing after a few inches. Under light microscopy, WH shows some structural anomalies, including trichorrhexis nodosa and tapered ends. WH can appear as part of several syndromes, such as Naxos disease (601214) and cardiofaciocutaneous syndrome (115150) (summary by Petukhova et al., 2009). See 278150 for a discussion of genetic heterogeneity of autosomal recessive woolly hair. [from OMIM]

Pachyonychia congenita (PC) is characterized by hypertrophic nail dystrophy, painful palmoplantar keratoderma and blistering, oral leukokeratosis, pilosebaceous cysts (including steatocystoma and vellus hair cysts), palmoplantar hyperhydrosis, and follicular keratoses on the trunk and extremities. [from GeneReviews]