Schinzel-Giedion midface retraction syndrome.
Incidence
Schinzel-Giedion midface retraction syndrome is presumed to be inherited as autosomal recessive on the basis of several pairs of affected sibs with normal parents. No specific gene or chromosome region has been identified, but recently de novo mutations of SETBP1 have been associated with this syndrome in 12 cases. There are 44 reported families.
Clinical Characteristics
The craniofacial appearance is essential to the diagnosis. There is a pathognomonic \\\"midface retraction\\\" consisting of shallow orbits and midface hypoplasia with resulting prominence of the forehead. All reported patients have high forehead, large fontanelles and widely patent cranial sutures, particularly the metopic suture. The facial appearance is often described as coarse. Hypertelorism, flat nasal bridge, anteverted nares and lowset ears with protruding lobules are frequent. Nearly half the patients have choanal stenosis. Hydronephrosis is present in over 90% of cases. Mental deficiency is usually profound. Both hypotonia and spasticity are common and may occur at different times in the same patient. Seizures of varying types, often including infantile spasms, are reported in most patients. Central nervous system malformations, particularly agenesis of the corpus callosum are reported occasionally, but the major anomaly on cranial MRI is cerebral atrophy which has been documented to progress over time in many of the longer surviving patients. Other features, particularly skeletal findings, are helpful, but less specific. No generally accepted diagnostic guidelines exist.
Precipitants
None
Provocation Tests
None
Diagnostic Procedures
It is a clinical diagnosis. The craniofacial appearance is essential to the diagnosis. Hydronephrosis is present in over 90% of cases. Other features, particularly skeletal findings, are helpful, but less specific. No generally accepted diagnostic guidelines exist. Chromosome studies are normal in Schinzel-Giedion midface retraction syndrome, but de novo mutations of SETBP1 have been associated with this syndrome, and may be investigated.