Spondylocarpotarsal synostosis (SCT) syndrome is a skeletal dysplasia clinically characterized by postnatal progressive vertebral fusions frequently manifesting as block vertebrae, contributing to an undersized trunk and a disproportionate short stature, scoliosis, lordosis, carpal and tarsal synostosis, with club feet and a mild facial dysmorphism.
The prevalence of SCT syndrome is unknown.
While the clinical onset is postnatal, proper diagnosis becomes evident later in childhood. Primary clinical characteristics of SCT syndrome include progressive vertebral fusions manifesting as block vertebrae leading to an undersized trunk and a disproportionate short stature becoming apparent with physical growth. Scoliosis, lordosis, carpal and tarsal synostosis with club feet are frequent. A mild facial dysmorphism with a round face with frontal bossing and anteverted nostrils. Midline cleft palate, conductive hearing loss, joint laxity and dental enamel hypoplasia are uncommonly reported.
SCT syndrome is due to mutations in the FLNB gene (localized to 3p14.3) that encodes cytoskeletal protein filamin B.
Diagnosis is confirmed by skeletal x-rays and genetic testing. Radiographs demonstrates progressive vertebral fusions and lumbar spine, carpal and tarsal synostosis without rib anomalies. Occasionally, delayed ossification of epiphyses and bilateral epiphyseal femur dysplasia are reported.
Differential diagnosis may include isolated Klippel-Feil syndrome and other vertebral dysplasias, such as autosomal dominant spondylocostal dysplasia and multiple synostoses syndrome (see these terms).
SCT syndrome follows an autosomal recessive inheritance.
Management involves ophthalmologic, audiologic and spine assessments. Scoliosis is treated medically; no effective surgical intervention have been described. The cervical spine should be evaluated for features of instability prior to general anesthesia. Pain management is indispensable as patients suffer from much continuing physical pain due to the spinal deformities and fused block vertebrae.
SCT syndrome does not affect life expectancy.
Last update: July 2013