RESUMEN
We report on two siblings doubly heterozygous for null mutations in the recently identified AGS5 gene SAMHD1. The older female child showed mild intellectual disability with microcephaly. Her brother demonstrated a significant spastic paraparesis with normal intellect and head size. Both children had an unclassified chronic inflammatory skin condition with chilblains, and recurrent mouth ulcers. One child had a chronic progressive deforming arthropathy of the small and large joints, with secondary contractures. This family illustrate the remarkable phenotypic diversity accruing from mutations in genes associated with Aicardi-Goutières syndrome (AGS). The association of arthropathy with SAMHD1 mutations highlights a phenotypic overlap of AGS with familial autoinflammatory disorders such as chronic infantile neurological cutaneous and articular syndrome (CINCA). This family therefore illustrate the need to consider mutation analysis of SAMHD1 in non-specific inflammatory phenotypes of childhood. We propose that arthropathy with progressive contractures should now be considered part of the spectrum of Aicardi-Goutières syndrome because of SAMHD1 mutations.