A multifocal, multisystem form of Langerhans-cell histiocytosis. There is involvement of multiple organ systems including the bones, skin, liver, spleen, and lymph nodes. Patients are usually infants presenting with fever, hepatosplenomegaly, lymphadenopathy, bone and skin lesions, and pancytopenia.

Gorham-Stout disease (GSD) is a rare disease of massive osteolysis associated with proliferation and dilation of lymphatic vessels. GSD may affect any bone in the body and can be monostotic or polyostotic. Symptoms at presentation are dependent upon the location(s) of the disease; the most common symptom is localized pain. The disease may be discovered after a pathological fracture.

Fibromatosis arising from the soft tissues of the penis. It is characterized by the presence of spindle-shaped fibroblasts, and an infiltrative growth pattern. It causes the penis to bend when it becomes erect.

An episodic vasoconstriction resulting in discoloration of the skin and pain in the affected areas, often involving fingers or toes. Classically associated with triphasic color changes (white, blue, red) but may be biphasic. Often occurs in response to cold temperatures or emotional stress. May be primary or secondary to an underlying autoimmune disease.

Rotor syndrome is characterized by mild conjugated and unconjugated hyperbilirubinemia that usually begins shortly after birth or in childhood. Jaundice may be intermittent. Conjunctival icterus may be the only clinical manifestation.

Skoog (1948) defined knuckle pads as 'subcutaneous nodules on the dorsal aspect of the proximal interphalangeal joints.'

Tibial hemimelia is a rare anomaly characterized by deficiency of the tibia with relatively intact fibula. Jones et al. (1978) classified the anomaly into 4 types according to radiologic criteria. It may present as an isolated anomaly or be associated with a variety of skeletal and extraskeletal malformations. Tibial hemimelia may also constitute a part of a more complicated malformation complex or syndrome, such as the Gollop-Wolfgang complex (228250) and triphalangeal thumb-polysyndactyly syndrome (see 174500 and 188740) (Matsuyama et al., 2003). McKay et al. (1984) reviewed syndromes of congenital defects in which tibial hemimelia is a feature.

In the resting position, the tip of the thumb is on, or near, the palm, close to the base of the fourth or fifth finger.

A rare bone development disorder characterized by localized, asymmetric osteochondral overgrowth affecting single or multiple epiphyses, most commonly the distal femur, proximal tibia, and talus. The lesions are typically restricted to one side of the epiphysis, with the medial side being affected twice as often as the lateral side. The condition is usually diagnosed in children, and three times more often in boys than in girls. Patients present with pain, limitation in range of motion, and deformity or swelling of the affected joint.

Syndrome that is characterised by intellectual deficit, choroideraemia, acrokeratosis verruciformis, anhidrosis, and skeletal deformities. It has been observed in a single kindred. The syndrome is transmitted as an X-linked recessive trait and may be caused by a small X-chromosome deletion.

A chronic adhesive arachnoiditis in the spinal arachnoid, with root and spinal cord symptoms similar to those caused by pressure from a tumor.

This autosomal recessive neurodevelopmental disorder is characterized by pachygyria, impaired intellectual development, seizures, and diffuse localization of arachnoid cysts. It most likely represents a neuronal migration disorder within the lissencephaly spectrum (summary by Guzel et al., 2007).

A lethal malformation syndrome reported in 2 brothers of first-cousin parents with characteristics of hydrocephalus, cardiac malformation, dense bones and unusual facies with down-slanting palpebral fissures, bulbous nose, broad nasal bridge, micrognathia and a long upper lip. Transmission is likely autosomal recessive. There have been no further descriptions in the literature since 1984.

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).

Galloway-Mowat syndrome-7 (GAMOS7) is an autosomal recessive disorder characterized by developmental delay, microcephaly, and early-onset nephrotic syndrome (summary by Rosti et al., 2017). For a general phenotypic description and a discussion of genetic heterogeneity of GAMOS, see GAMOS1 (251300).

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).