However, since the X-linked mode of inheritance had been proposed for Roifman Syndrome, we additionally investigated X-chromosome variants found in only one of the two siblings; they either did not have any known implication in human genetic disorders or mouse abnormal phenotypes (genes ARSH and HS6ST2-AS1), or they had modest protein-damaging potential and insufficient match to Roifman Syndrome phenotype (genes AFF2 and SH3KBP1, for more details see Supplementary Data 1, Supplementary Tables 3–5 and Supplementary Note 2). Here, HS6ST2 is linked to Roifman syndrome.