Endocrine dysfunction, well reported in XRCC4-related MPD, is also observed in other DNA repair defects, including DNA2, BLM, NSMCE2-related MPD [MIM#615807, MIM#210900, MIM#617253], but also in other MPD such as Majewski syndrome [35]. The gene discussed is BLM; the disease is short-rib thoracic dysplasia 6 with or without polydactyly.