Otopalatodigital Syndrome, Type Ii (OPD2)

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MedlinePlus Genetics: ⁴² Otopalatodigital syndrome type 2 is a disorder primarily involving abnormalities in skeletal development. It is a member of a group of related conditions called otopalatodigital spectrum disorders, which also includes otopalatodigital syndrome type 1, frontometaphyseal dysplasia, Melnick-Needles syndrome, and terminal osseous dysplasia. In general, these disorders involve hearing loss caused by malformations in the tiny bones in the ears (ossicles), problems in the development of the roof of the mouth (palate), and skeletal abnormalities involving the fingers or toes (digits). Otopalatodigital syndrome type 2 also tends to cause problems in other areas of the body, such as the brain and heart.People with otopalatodigital syndrome type 2 have characteristic facial features including wide-set and downward-slanting eyes; prominent brow ridges; a broad, flat nose; and a very small lower jaw and chin (micrognathia). Affected individuals often have abnormalities of the fingers and toes, such as unusual curvature of the fingers (camptodactyly) and shortened or absent thumbs and big toes. People with otopalatodigital syndrome type 2 usually have short stature, abnormally curved (bowed) bones in the arms and legs, and other abnormal or absent bones. Underdeveloped ribs can cause problems with breathing in affected individuals. Some people with this condition have an opening in the roof of the mouth (a cleft palate) or hearing loss.In addition to skeletal abnormalities, individuals with otopalatodigital syndrome type 2 may have developmental delay, increased fluid in the center of the brain (hydrocephalus), protrusion of the abdominal organs through the navel (omphalocele), heart defects, chest abnormalities, obstruction of the ducts between the kidneys and bladder (ureters), and, in males, opening of the urethra on the underside of the penis (hypospadias).Males with otopalatodigital syndrome type 2 generally have much more severe signs and symptoms compared to affected females. Males with this condition typically do not survive past infancy because of respiratory failure due to an underdeveloped rib cage.

MalaCards based summary: Otopalatodigital Syndrome, Type Ii, also known as otopalatodigital syndrome type 2, is related to frontometaphyseal dysplasia and terminal osseous dysplasia. An important gene associated with Otopalatodigital Syndrome, Type Ii is FLNA (Filamin A), and among its related pathways/superpathways are Cytoskeletal Signaling and MAPK signaling pathway. The drugs Valproic acid and Neurotransmitter Agents have been mentioned in the context of this disorder. Affiliated tissues include bone, heart and brain, and related phenotypes are hearing impairment and skeletal dysplasia

OMIM®: ⁵⁷ Otopalatodigital syndrome-2 is 1 of 4 otopalatodigital syndromes caused by mutations in the FLNA gene. The disorders, which include frontometaphyseal dysplasia (FMD1; 305620), otopalatodigital syndrome-1 (OPD1; 311300), and Melnick-Needles syndrome (MNS; 309350), constitute a phenotypic spectrum. At the mild end of the spectrum, males with OPD1 have cleft palate and mild skeletal anomalies with conductive deafness caused by ossicular anomalies. FMD is characterized by a generalized skeletal dysplasia, deafness and urogenital defects. Males with OPD2 have disabling skeletal anomalies in addition to variable malformations in the hindbrain, heart, intestines, and kidneys that frequently lead to perinatal death. The most severe phenotype, MNS, is characterized by a skeletal dysplasia in the heterozygote. Affected males exhibit severe malformations similar to those observed in individuals with OPD2, resulting in prenatal lethality or death in the first few months of life (review by Robertson, 2005). Verloes et al. (2000) suggested that these disorders constitute a single entity, which they termed 'frontootopalatodigital osteodysplasia.' (304120) (Updated 08-Dec-2022)

Disease Ontology: ¹¹ An otopalatodigital syndrome spectrum disorder characterized by disabling skeletal anomalies and variable malformations in the hindbrain, heart, intestines, and kidneys that frequently lead to perinatal death in males and less severe phenotypes in females that has material basis in hemizygous or heterozygous mutation in exons 3, 4 ,or 5 in males or exons 28 or 29 in females of FLNA on chromosome Xq28.

GARD: ¹⁹ A severe form of otopalatodigital syndrome spectrum disorder, and is characterized by dysmorphic facies, severe skeletal dysplasia affecting the axial and appendicular skeleton, extraskeletal anomalies (including malformations of the brain, heart, genitourinary system, and intestine) and poor survival.

Orphanet: ⁵⁸ A severe form of otopalatodigital syndrome spectrum disorder, and is characterized by dysmorphic facies, severe skeletal dysplasia affecting the axial and appendicular skeleton, extraskeletal anomalies (including malformations of the brain, heart, genitourinary system, and intestine) and poor survival.

UniProtKB/Swiss-Prot: ⁷³ Congenital bone disorder that is characterized by abnormally modeled, bowed bones, small or absent first digits and, more variably, cleft palate, posterior fossa brain anomalies, omphalocele and cardiac defects.

Clinical features from OMIM®:

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