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).

Agnathia-otocephaly (AGOTC) is a rare condition characterized by mandibular hypoplasia or agnathia, ventromedial auricular malposition (melotia) and/or auricular fusion (synotia), and microstomia with oroglossal hypoplasia or aglossia. Holoprosencephaly is the most commonly identified association, but skeletal, genitourinary, and cardiovascular anomalies, and situs inversus have been reported. The disorder is almost always lethal (review by Faye-Petersen et al., 2006).

The imino acids, proline and hydroxyproline, share a renal tubular reabsorptive mechanism with glycine. Iminoglycinuria (IG), a benign inborn error of amino acid transport, is also a normal finding in neonates and infants under 6 months of age (Chesney, 2001). Early studies of families with iminoglycinuria suggested genetic complexity, with homozygotes developing IG and heterozygotes manifesting only hyperglycinuria (HG; 138500) (summary by Broer et al., 2008). Iminoglycinuria also occurs as part of the generalized amino aciduria of the Fanconi renotubular syndrome (134600).

Smith-Magenis syndrome (SMS) is characterized by distinctive physical features (particularly coarse facial features that progress with age), developmental delay, cognitive impairment, behavioral abnormalities, sleep disturbance, and childhood-onset abdominal obesity. Infants have feeding difficulties, failure to thrive, hypotonia, hyporeflexia, prolonged napping or need to be awakened for feeds, and generalized lethargy. The majority of individuals function in the mild-to-moderate range of intellectual disability. The behavioral phenotype, including significant sleep disturbance, stereotypies, and maladaptive and self-injurious behaviors, is generally not recognized until age 18 months or older and continues to change until adulthood. Sensory issues are frequently noted; these may include avoidant behavior, as well as repetitive seeking of textures, sounds, and experiences. Toileting difficulties are common. Significant anxiety is common as are problems with executive functioning, including inattention, distractibility, hyperactivity, and impulsivity. Maladaptive behaviors include frequent outbursts / temper tantrums, attention-seeking behaviors, opposition, aggression, and self-injurious behaviors including self-hitting, self-biting, skin picking, inserting foreign objects into body orifices (polyembolokoilamania), and yanking fingernails and/or toenails (onychotillomania). Among the stereotypic behaviors described, the spasmodic upper-body squeeze or "self-hug" seems to be highly associated with SMS. An underlying developmental asynchrony, specifically emotional maturity delayed beyond intellectual functioning, may also contribute to maladaptive behaviors in people with SMS.

A chronic autoimmune disorder that belongs to the mucous membrane pemphigoid disorders. It is characterized by bilateral scarring and opacification of the conjunctivae. It presents with pain and burning sensation in the eyes and photophobia. It leads to blindness.

Malignant melanoma is a neoplasm of pigment-producing cells called melanocytes that occurs most often in the skin, but may also occur in the eyes, ears, gastrointestinal tract, leptomeninges, and oral and genital mucous membranes (summary by Habif, 2010). Genetic Heterogeneity of Susceptibility to Cutaneous Malignant Melanoma The locus for susceptibility to familial cutaneous malignant melanoma-1 (CMM1) has been mapped to chromosome 1p36. Other CMM susceptibility loci include CMM2 (155601), caused by variation in the CDKN2A gene (600160) on chromosome 9p21; CMM3 (609048), caused by variation in the CDK4 gene (123829) on chromosome 12q14; CMM4 (608035), mapped to chromosome 1p22; CMM5 (613099), caused by variation in the MC1R gene (155555) on chromosome 16q24; CMM6 (613972), caused by variation in the XRCC3 gene (600675) on chromosome 14q32; CMM7 (612263), mapped to chromosome 20q11; CMM8 (614456), caused by variation in the MITF gene (156845) on chromosome 3p13; CMM9 (615134), caused by variation in the TERT gene (187270) on chromosome 5p15; and CMM10 (615848), caused by mutation in the POT1 gene (606478) on chromosome 7q31. Somatic mutations causing malignant melanoma have also been identified in several genes, including BRAF (164757), STK11 (602216), PTEN (601728), TRRAP (603015), DCC (120470), GRIN2A (138253), ZNF831, BAP1 (603089), and RASA2 (601589). A large percentage of melanomas (40-60%) carry an activating somatic mutation in the BRAF gene, most often V600E (164757.0001) (Davies et al., 2002; Pollock et al., 2003).

Oculomotor-levator synkinesis (OCLEVS) is characterized by abnormal eyelid elevation or retraction during ipsilateral adduction. The disorder most likely results from aberrant innervation of extraocular muscles by the oculomotor nerve (cranial nerve III). Normally, the levator muscle is served by the superior branch of CN3 and the medial rectus muscle is served by the inferior branch of CN3. The clinical features suggest synkinesis between the medial rectus and levator muscle branches. The disorder can be classified as a congenital cranial dysinnervation disorder (CCDD) and also shows features of congenital fibrosis of the extraocular muscles (CFEOM; see 135700) (summary by Pang et al., 1986 and Khan et al., 2004) See also oculomotor-abducens synkinesis (OCABSN; 619215), caused by mutation in the ACKR3 gene (610376) on chromosome 2q37.

An exceedingly rare, benign, congenital, corneal tumour characterised by bilateral opacification of the cornea with superficial greyish layers and irregular raised whitish plaques, as well as fine blood vessels covering the central cornea, and intact peripheral corneal borders. No other ocular or systemic abnormality is noted. The pattern of inheritance described in the affected family is consistent with X-linked transmission.

Stickler syndrome is a connective tissue disorder that can include ocular findings of myopia, cataract, and retinal detachment; hearing loss that is both conductive and sensorineural; midfacial underdevelopment and cleft palate (either alone or as part of the Robin sequence); and mild spondyloepiphyseal dysplasia and/or precocious arthritis. Variable phenotypic expression of Stickler syndrome occurs both within and among families; interfamilial variability is in part explained by locus and allelic heterogeneity.

Nemaline myopathy-2 (NEM2) is an autosomal recessive skeletal muscle disorder with a wide range of severity. The most common clinical presentation is early-onset (in infancy or childhood) muscle weakness predominantly affecting proximal limb muscles. Muscle biopsy shows accumulation of Z-disc and thin filament proteins into aggregates named 'nemaline bodies' or 'nemaline rods,' usually accompanied by disorganization of the muscle Z discs. The clinical and histologic spectrum of entities caused by variants in the NEB gene is a continuum, ranging in severity. The distribution of weakness can vary from generalized muscle weakness, more pronounced in proximal limb muscles, to distal-only involvement, although neck flexor weakness appears to be rather consistent. Histologic patterns range from a severe usually nondystrophic disturbance of the myofibrillar pattern to an almost normal pattern, with or without nemaline bodies, sometimes combined with cores (summary by Lehtokari et al., 2014). Genetic Heterogeneity of Nemaline Myopathy See also NEM1 (255310), caused by mutation in the tropomyosin-3 gene (TPM3; 191030) on chromosome 1q22; NEM3 (161800), caused by mutation in the alpha-actin-1 gene (ACTA1; 102610) on chromosome 1q42; NEM4 (609285), caused by mutation in the beta-tropomyosin gene (TPM2; 190990) on chromosome 9p13; NEM5A (605355), also known as Amish nemaline myopathy, NEM5B (620386), and NEM5C (620389), all caused by mutation in the troponin T1 gene (TNNT1; 191041) on chromosome 19q13; NEM6 (609273), caused by mutation in the KBTBD13 gene (613727) on chromosome 15q22; NEM7 (610687), caused by mutation in the cofilin-2 gene (CFL2; 601443) on chromosome 14q13; NEM8 (615348), caused by mutation in the KLHL40 gene (615340), on chromosome 3p22; NEM9 (615731), caused by mutation in the KLHL41 gene (607701) on chromosome 2q31; NEM10 (616165), caused by mutation in the LMOD3 gene (616112) on chromosome 3p14; and NEM11 (617336), caused by mutation in the MYPN gene (608517) on chromosome 10q21. Several of the genes encode components of skeletal muscle sarcomeric thin filaments (Sanoudou and Beggs, 2001). Mutations in the NEB gene are the most common cause of nemaline myopathy (Lehtokari et al., 2006).

Schopf-Schulz-Passarge syndrome (SSPS) is an autosomal recessive disorder characterized by a constellation of multiple eyelid cysts, hypodontia, hypotrichosis, palmoplantar hyperkeratosis, and onychodystrophy (summary by Mallaiah and Dickinson, 2001).

Gaucher disease (GD) encompasses a continuum of clinical findings from a perinatal lethal disorder to an asymptomatic type. The identification of three major clinical types (1, 2, and 3) and two other subtypes (perinatal-lethal and cardiovascular) is useful in determining prognosis and management. GD type 1 is characterized by the presence of clinical or radiographic evidence of bone disease (osteopenia, focal lytic or sclerotic lesions, and osteonecrosis), hepatosplenomegaly, anemia and thrombocytopenia, lung disease, and the absence of primary central nervous system disease. GD types 2 and 3 are characterized by the presence of primary neurologic disease; in the past, they were distinguished by age of onset and rate of disease progression, but these distinctions are not absolute. Disease with onset before age two years, limited psychomotor development, and a rapidly progressive course with death by age two to four years is classified as GD type 2. Individuals with GD type 3 may have onset before age two years, but often have a more slowly progressive course, with survival into the third or fourth decade. The perinatal-lethal form is associated with ichthyosiform or collodion skin abnormalities or with nonimmune hydrops fetalis. The cardiovascular form is characterized by calcification of the aortic and mitral valves, mild splenomegaly, corneal opacities, and supranuclear ophthalmoplegia. Cardiopulmonary complications have been described with all the clinical subtypes, although varying in frequency and severity.

Heterozygous protein C deficiency is characterized by recurrent venous thrombosis. However, many adults with heterozygous disease may be asymptomatic (Millar et al., 2000). Individuals with decreased amounts of protein C are classically referred to as having type I deficiency and those with normal amounts of a functionally defective protein as having type II deficiency (Bertina et al., 1984). Acquired protein C deficiency is a clinically similar disorder caused by development of an antibody against protein C. Clouse and Comp (1986) reviewed the structural and functional properties of protein C and discussed both hereditary and acquired deficiency of protein C.

ALS2-related disorder involves retrograde degeneration of the upper motor neurons of the pyramidal tracts and comprises a clinical continuum of the following three phenotypes: Infantile ascending hereditary spastic paraplegia (IAHSP), characterized by onset of spasticity with increased reflexes and sustained clonus of the lower limbs within the first two years of life, progressive weakness and spasticity of the upper limbs by age seven to eight years, and wheelchair dependence in the second decade with progression toward severe spastic tetraparesis and a pseudobulbar syndrome caused by progressive cranial nerve involvement. Juvenile primary lateral sclerosis (JPLS), characterized by upper motor neuron findings of pseudobulbar palsy and spastic quadriplegia without dementia or cerebellar, extrapyramidal, or sensory signs. Juvenile amyotrophic lateral sclerosis (JALS or ALS2), characterized by onset between ages three and 20 years. All affected individuals show a spastic pseudobulbar syndrome (spasticity of speech and swallowing) together with spastic paraplegia. Some individuals are bedridden by age 12 to 50 years.

Oculocerebral hypopigmentation syndrome, Cross type is a rare congenital syndrome characterized by cutaneous and ocular hypopigmentation, various ocular anomalies (e.g. corneal and lens opacity, spastic ectropium, and/or nystagmus), growth deficiency, intellectual deficit and other progressive neurologic anomalies such as spastic tetraplegia, hyperreflexia, and/or athetoid movements. The clinical picture varies among patients and may also include other anomalies such as urinary tract abnormalities, Dandy-Walker malformations, and/or bilateral inguinal hernia.

Complex cortical dysplasia with other brain malformations-7 is an autosomal dominant, clinically heterogeneous disorder showing a wide spectrum of abnormalities of cortical brain development. The most severely affected patients are fetuses with microlissencephaly, absence of the cortical plate, agenesis of the corpus callosum, and severely hypoplastic brainstem and cerebellum. Other patients have lissencephaly, polymicrogyria, cortical dysplasia, or neuronal heterotopia. Those with less severe malformations can survive, but usually have some degree of neurologic impairment, such as mental retardation, seizures, and movement abnormalities (summary by Chang et al., 2006; Fallet-Bianco et al., 2014). For a discussion of genetic heterogeneity of CDCBM, see CDCBM1 (614039).

Some ectodermal dysplasias are here classified as congenital disorders characterized by abnormal development in 2 or more ectodermal structures (hair, nails, teeth, and sweat glands) without other systemic findings. Ectodermal dysplasia of the hair/nail type is a rare congenital condition characterized by hypotrichosis and nail dystrophy without nonectodermal or other ectodermal manifestations. Hypotrichosis usually occurs after birth with varying degrees of severity, ranging from mild hair loss to complete atrichia, including the loss of scalp hair, beard, eyebrows, eyelashes, axillary hair, and pubic hair. Nail dystrophy affects all 20 digits by causing short fragile nails or spoon nails (koilonychia) (summary by Lin et al., 2012).

Developmental delay, impaired speech, and behavioral abnormalities (DDISBA) is characterized by global developmental delay apparent from early childhood. Intellectual disability can range from mild to severe. Additional variable features may include dysmorphic facial features, seizures, hypotonia, motor abnormalities such as Tourette syndrome or dystonia, and hearing loss (summary by Cousin et al., 2021).