<i>LRP5</i> Variant Without Pseudoglioma in a Young Man With Fragility Fractures

Osteoporosis in children and young adults is relatively rare. Hereditary causes are often overlooked in the absence of a positive family history. We report a 29-year-old male presenting with recurrent fragility fractures since 6 years of age. Secondary causes, such as celiac disease, inflammatory disorders, and hypogonadism, were ruled out. Family history was negative for any bone disease. Exome sequencing revealed 2 variants of <i>LRP5</i> gene-intron 5 c.1015 + 1G > A and exon 5 c.892C > T. Although the former variant has been described in literature as a cause of osteoporosis in homozygous state only, it manifested as osteoporosis in our patient, in the heterozygous state, in presence of a second variant of uncertain significance. However, eye involvement, which is classically seen in "osteoporosis-pseudoglioma syndrome" homozygote, was absent in our patient. Genetic analysis of the parents revealed father to be a carrier of intron 5 c.1015 + 1G > A and mother exon 5 c.892C > T variants of the <i>LRP5</i> gene. However, none of them had osteoporosis on bone densitometry. The patient was subsequently treated with IV zoledronic acid (planned to be administered annually) and showed improvement in bone density by 11% at the spine and 9.5% at the left femur; there were no further fractures over 1 year of follow-up.