ESPE Abstracts

Introduction: Osteoporosis pseudoglioma syndrome (OPPG) is a rare autosomal recessive disease which is caused by mutations in the low-density lipoprotein receptor-related protein 5 (LRP5) gene and is characterized by severe early – onset osteoporosis and vitreoretinal complications leading to blindness by young adulthood.

Case presentation: We present a case of an 8 years old boy, who was initially referred to our department by the Orthopaedic team due to radiology findings of osteoporosis when investigated for a six-month history of thoracolumbar pain. His physical activity was significantly reduced due to pain. He was born at 36w+5d by normal delivery and required admission to the Neonatal Unit for 2 days due to perinatal stress. His parents were not consanguineous. At the age of 3 months he was diagnosed with severely impaired vision due to retinal hemorrhage. Hypotonia and gross motor delay were also noted from infancy. At the age of 4 years old he underwent orchidopexy for bilateral undescended testis. Despite growing just below the 3rd centile for height and weight as well, he started gaining weight during childhood reaching the 85th centile by 8 years. Extensive hematological and biochemical tests showed normal ALP, Ca, P and PTH values, vitamin D deficiency and increased CTX levels. Bone mineral density (BMD) was assessed by DEXA scan and confirmed the findings of severe osteoporosis (lumbar spine 0.204gr/cm2, Z-score: -5.6). Dental and ENT examination was normal. At that time, he sustained an atraumatic fracture of the left femur and left radius. The combination of osteoporosis and vitreoretinal pathology raised the suspicion of OPPG syndrome. Direct sequencing of the LRP5 gene revealed the homozygous deletion c.2409_2503+79del (G804_G835delfsX49) in exon/intron 11. He was commenced on Calcium and Vitamin D supplements and bisphosphonate treatment with periodic intravenous zoledronic acid. BMD measurements in other family members revealed that his brother had osteopenia, his sister had a reduced BMD (Z-score -2.9) and scoliosis while his mother had premenopausal osteoporosis. Genetic testing for the family members is pending.

Conclusion: Although OPPG is a rare genetic disease, clinicians should consider its diagnosis in cases of severe osteoporosis with early onset of impaired vision.