Otopalatodigital Syndrome Type 1

A disorder that is the mildest form of otopalatodigital syndrome spectrum disorder, and is characterized by a generalized skeletal dysplasia, mild intellectual disability, conductive hearing loss, and typical facial anomalies.

Epidemiology

To date, more than 100 cases have been described in the world literature.

Clinical description

OPD1 is a congenital disorder characterized by generalized skeletal dysplasia which include camptodactyly, long spatulate fingers, short first digits (''tree frog'' hands and feet), pectus carinatum, mild campomelia, mild femoral bowing, limitation of joint movement (elbow extension, wrist abduction) and malformed auditory ossicles leading to conductive hearing loss in some individuals. Additional features include typical craniofacial anomalies (occipital prominence, frontal bossing with prominent supraorbital ridges, flat nasal bridge, hypertelorism, microstomia, dental abnormalities, and cleft palate (pugilistic face)). In affected females, a similar but usually milder spectrum of expressivity is observed.

Etiology

OPD1 is caused by gain of function mutations in the gene FLNA (Xq28) that encodes filamin A. However the pathogenesis of OPD1 is still elusive. OPD1 is allelic with 4 other skeletal dysplasias (OPD2, Melnick-Needles syndrome (MNS), terminal osseous dysplasia - pigmentary defects (TOD) and frontometaphyseal dysplasia (FMD)).

Genetic counseling

OPD1 is inherited in an X-linked dominant manner. Male-to-male transmission has not been reported. The risk of transmitting the mutation in each pregnancy is 50%; males inheriting the mutation will be affected while females who inherit the mutation have a broad range of phenotypic expression.