TASP1 is deleted in an infant with developmental delay, microcephaly, distinctive facial features, and multiple congenital anomalies

We report a 20p12.1 homozygous deletion including exons 5-10 of the TASP1 gene in an infant with developmental delay, acquired microcephaly, distinctive facial features, and multiple congenital anomalies involving skeletal, cardiac, and renal systems. TASP1 encodes taspase 1 which is responsible for cleaving, thus activating, a number of transcription factors including the mixed lineage leukemia 1 (MLL1). Taspase 1-deficient mice showed early lethality, skeletal abnormalities, and growth failure, which support a potentially causal role of TASP1 deletion in this infant. Furthermore, the infant reported here had many of the features seen in Wiedemann-Steiner syndrome which is caused by MLL1 defects. Such observation further supports that TASP1 is a novel disease-related gene that is associated with a disease phenotype overlapping with Wiedemann-Steiner syndrome as both are caused by defects in the same pathway.