Monoallelic and biallelic &ITCREB3L1 &ITvariant causes mild and severe osteogenesis imperfecta, respectively

Purpose: Osteogenesis imperfecta (OI) is a heritable skeletal dysplasia. Dominant pathogenic variants in COLIA1 and COLIA2 explain the majority of OI cases. At least 15 additional genes have been identified, but those still do not account for all OI phenotypes that present. We sought the genetic cause of mild and lethal OI phenotypes in an unsolved family.& para;& para;Methods: We performed exome sequencing on seven members of the family, both affected and unaffected.& para;& para;Results: We identified a variant in cyclic AMP responsive element binding protein 3-like 1 (CREB3L1) in a consanguineous family. The variant caused a prenatal/perinatal lethal OI in homozygotes, similar to that seen in OI type II as a result of mutations in type I collagen genes, and a mild phenotype (fractures, blue sclerae) in multiple heterozygous family members. CREB3L1 encodes old astrocyte specifically induced substance (OASIS), an endoplasmic reticulum stress transducer. The variant disrupts a DNA-binding site and prevents OASIS from acting on its transcriptional targets including SEC24D, which encodes a component of the coat protein II complex.& para;& para;Conclusion: This report confirms that CREB3L1 is an OI-related gene and suggests the pathogenic mechanism of CREB3L1-associated OI involves the altered regulation of proteins involved in cellular secretion.