While truncating mutations and deletions in tnxb, resulting in Tenascin X deficiency [56,57], were found in patients with major and minor diagnostic criteria for cEDS type [56], tnxb haploinsufficiency has been found in patients with an autosomal dominant form of hEDS who did not show easy bruising and skin hyperextensibility, like in tnx deficiency [58]. Here, TNXB is linked to hyperinsulinemic hypoglycemia, familial, 4.