ASC1 complex related conditions: Two novel paediatric patients with TRIP4 pathogenic variants and review of literature.

Pathogenic variants in the genes encoding for the ASC1 complex were recently reported in patients with congenital fractures, joint contractures, neonatal hypotonia and respiratory distress. Here we report two male children with biallelic TRIP4 pathogenic loss of function variants. The first child presented with foetal bradykinesia, neonatal respiratory distress, central and peripheral hypotonia, constipation, hyperlaxity, left uretero-hydronephrosis and post-obstructive kidney dysplasia. The second had severe central and peripheral neonatal hypotonia, feeding difficulties, kyphosis, developmental delay and hyperlaxity. Detailed review of all reported cases with ASCC1 (12 patients) and TRIP4 (18 patients) variants highlights striking genotype-phenotype correlations. This is the fourth report of patients with TRIP4 variants and the first description of post-obstructive kidney dysplasia in this condition.