More severe phenotypic manifestations were observed in this patient as compared to one carrying only the homozygous WDR62 stop mutation [17], which was attributed to the modifying effects of TBCD. In case of Seckel syndrome, only a digenic inheritance pattern has been reported, with heterozygous mutations of CDK5RAP2 and CEP152 [36]. Here, TBCD is linked to microcephalic primordial dwarfism.