Histological analysis of Tbx1-knockout palate with complete cleft palate at postnatal day 1 showed aplasia of secondary palates associated with a small mandible and a small tongue compared to wild type littermates.
T-box transcription factor, TBX1, is the major candidate gene for 22q11.2 deletion syndrome (DiGeorge/ Velo-cardio-facial syndrome) characterized by facial defects, thymus hypoplasia, cardiovascular anomalies and cleft palates.
Cleft palate was observed in both conditional knockout and over-expression mice, consistent with the craniofacial/tooth defects associated with TBX1 deletion and the gene duplication that leads to 22q11.2DS.
Two of the most common phenotypic categories, congenital heart disease and cleft palate, have been proposed to have a common genetic relationship to the deleted T-box 1 gene (TBX1).
Shprintzen syndrome (velo-cardio-facial, VCFS) is a very rare morbid entity, seen in either familial or sporadic forms, with major clinical findings such as facial dysmorphism, cleft palate, cardiovascular (especially conotruncal-anomalies), mild/moderate mental retardation, or, more commonly, observed learning difficulty.
Moreover, Tbx1-/- mice displayed a wide range of developmental anomalies encompassing almost all of the common DGS/VCFS features, including hypoplasia of the thymus and parathyroid glands, cardiac outflow tract abnormalities, abnormal facial structures, abnormal vertebrae and cleft palate.