Novel 4-bp Intronic Deletion (c.1560+3_1560+6del) in LEMD3 in a Korean Patient With Osteopoikilosis.

Osteopoikilosis is an autosomal dominant bone disorder characterized by symmetric multiple osteosclerotic lesions throughout the axial and appendicular skeleton. Pathogenic variants in the LEMD3 have been identified as the cause of osteopoikilosis. LEMD3 encodes an inner nuclear membrane protein that interacts with bone morphogenetic protein (BMP) and transforming growth factor (TGF)-β pathways. We report the case of a 19-year-old man presenting with lower back pain and sciatica. His radiograph revealed bilateral and symmetrical multiple osteosclerotic bone lesions in both scapular areas. Sanger sequencing of LEMD3 revealed a four-base-pair deletion in intron 2 (c.1560+3_1560+6del), which was inherited from his father. We found that this four-base-pair deletion in intron 2 causes aberrant splicing and consequent deletion of exon 2. To the best of our knowledge, this is the first report of genetically confirmed osteopoikilosis in Korea.