Further Exploring the TRRAP Genotype–Phenotype Correlations: Report of Three New Patients With A Focus on Skeletal Anomalies

TRRAP encodes a multidomain pseudokinase involved in histone acetyltransferase complexes. TRRAP pathogenic variants were linked to neurodevelopmental disorders, intellectual disability, congenital anomalies, and hearing loss. We report on three unrelated patients with TRRAP missense variants. Patient #1, a girl with severe intellectual disability, autism features, and preaxial polydactyly, displays the c.5575C>T, p.(Arg1859Cys) variant. Patient #2, a boy with developmental delay and facial anomalies, harbors the c.5647G>A, p.(Gly1883Arg) variant. Patient #3, a girl with developmental delay, epilepsy, and renal artery stenosis, carries the c.8572C>T, p.(Arg2858Trp) variant. These new cases broaden the TRRAP phenotypic spectrum, updating genotype-phenotype correlations. Osteoclast differentiation in Patient #1 and TRRAP expression in osteoclasts and osteoblasts were analyzed, leading to the assumption of a role of TRRAP in bone remodeling and in the observed skeletal anomalies.