The mucins can act as the protective barrier or luminal sensor for gut immunity and regulate gut microbiota.63 Also, the increased gastric mucin was observed in the treatment of chronic constipation with Lubiprostone.64 More importantly, the mucin gene mutation was reported in multiple ASD cohorts.42,65,66 The association analysis between functional SNVs with microbes in this current study revealed the involvement of SNVs within MUC family genes in the interaction between gut microbiota of constipated ASD. Here, MUC5AC is linked to Chronic constipation.