Neurofibromatosis 1 (NF1) is a multisystem disorder characterized by multiple café au lait macules, intertriginous freckling, multiple cutaneous neurofibromas, and learning disability or behavior problems. About half of people with NF1 have plexiform neurofibromas, but most are internal and not suspected clinically. Plexiform neurofibromas can cause pain, neurologic deficits, and abnormalities of involved or adjacent structures. Less common but potentially more serious manifestations include optic nerve and other central nervous system gliomas, malignant peripheral nerve sheath tumors, scoliosis, tibial dysplasia, vasculopathy, and gastrointestinal, endocrine, or pulmonary disease.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Dyschromatosis universalis hereditaria (DUH) is a rare autosomal dominant genodermatosis characterized by irregularly shaped asymptomatic hyper- and hypopigmented macules that appear in infancy or early childhood and occur in a generalized distribution over the trunk, limbs, and sometimes the face. Involvement of the palms or soles is unusual. Abnormalities of hair and nails have been reported, and DUH may be associated with abnormalities of dermal connective tissue, nerve tissue, or other systemic complications (summary by Zhang et al., 2013). For a discussion of genetic heterogeneity of DUH, see DUH1 (127500).

Cole disease (COLED) is a rare autosomal dominant disorder characterized by congenital or early-onset punctate keratoderma associated with irregularly shaped hypopigmented macules, which are typically found over the arms and legs but not the trunk or acral regions. Skin biopsies of palmoplantar lesions show nonspecific changes including hyperorthokeratosis, hypergranulosis, and acanthosis. Hypopigmented areas of skin, however, reveal a reduction in melanin content in keratinocytes but not in melanocytes, as well as hyperkeratosis and a normal number of melanocytes. Ultrastructurally, melanocytes show a disproportionately large number of melanosomes in the cytoplasm and dendrites, whereas keratinocytes show a paucity of these organelles, suggestive of impaired melanosome transfer (summary by Eytan et al., 2013). Some patients also exhibit calcinosis cutis or early-onset calcific tendinopathy (Eytan et al., 2013).

Amyloidosis cutis dyschromica (ACD), a rare form of primary localized cutaneous amyloidosis, is a pigmentary disorder in which keratinocyte-derived amyloid is deposited in the skin. Onset occurs before puberty and involves macular or reticulate hyperpigmentation admixed with symmetrically distributed guttate hypopigmented and hyperpigmented lesions. ACD can be distinguished from other conditions with similar clinical findings by a skin biopsy in which amyloid deposition in the papillary dermis is seen. Specific features that set ACD apart from the more common macular and lichenoid variants of primary cutaneous amyloidosis include dotted, reticular, or diffuse hyperpigmentation admixed with lentil-sized hypopigmented macules; mild or no associated pruritus; and, on histologic examination of skin from both hyper- and hypopigmented lesions, amyloid deposition confined to the papillary dermis, in close proximity to the epidermis (Huang et al. (2009); Mahon et al., 2016). For a discussion of genetic heterogeneity of primary localized cutaneous amyloidosis, see 105250.

Teebi hypertelorism syndrome-1 (TBHS1) is an autosomal dominant disorder characterized by hypertelorism with upslanting palpebral fissures, prominent forehead, broad and depressed nasal bridge with short nose, thick eyebrows, and widow's peak. Additional features include small broad hands with mild interdigital webbing and shawl scrotum. Umbilical malformations, cardiac defects, natal teeth, cleft lip/palate, congenital diaphragmatic hernia, and malformations of the central nervous system (ventriculomegaly, abnormal corpus callosum) have also been reported. Development is typically normal, although some patients with developmental delays have been reported (summary by Bhoj et al., 2015). Genetic Heterogeneity of Teebi Hypertelorism Syndrome Teebi hypertelorism syndrome-2 (TBHS2; 619736) is caused by mutation in the CDH11 gene (600023) on chromosome 16q21.