Otomo Takanobu, Yamamoto Takehisa, Fujikawa Yasuhiro, Shimotsuji Tsunesuke, Ozono Keiichi
Department of Pediatrics, Minoh City Hospital, Osaka, Japan ; Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
Clin Pediatr Endocrinol. 2011 Jan;20(1):7-12. doi: 10.1297/cpe.20.7. Epub 2011 Mar 26.
This present report concerns an infantile patient with mucolipidosis II, who showed transient cortical bone hyperostosis followed by severe osteopenia. The diagnosis of mucolipidosis II was made based on the leakage of lysosomal enzymes in serum and conditioned media of the patient's skin fibroblasts, low activity of lysosomal enzymes of the fibroblasts and mutation of c.2086_2089insC (p.L697fs) and c.3565C>T (p.R1189X) in the GNPTAB gene. Bone X-ray analysis demonstrated a periosteal reaction and elevated bone resorption at the age of 2 mo. Bone markers, including alkaline phosphatase, osteocalcin and urine deoxypyridinoline, also indicated a high turnover of bone metabolism; however, no apparent rickets-like changes and no increased levels of PTH were observed. Elevated bone resorption is possibly associated with the leakage of lysosomal enzyme from osteoclasts into bone matrices. Bone formation gradually reduced, and increased bone resorption persisted. This led to severe osteopenia at the age of 6 mo. Characteristic bone findings may contribute to early diagnosis of mucolipidosis II, but their pathogenesis remains to be clarified.
本报告涉及一名患有II型粘脂贮积症的婴儿患者，该患者出现短暂性皮质骨增生，随后出现严重骨质减少。II型粘脂贮积症的诊断基于患者皮肤成纤维细胞血清和条件培养基中溶酶体酶的泄漏、成纤维细胞溶酶体酶活性低下以及GNPTAB基因中c.2086_2089insC（p.L697fs）和c.3565C>T（p.R1189X）的突变。骨X线分析显示2个月大时出现骨膜反应和骨吸收增加。包括碱性磷酸酶、骨钙素和尿脱氧吡啶啉在内的骨标志物也表明骨代谢转换率高；然而，未观察到明显的佝偻病样改变，甲状旁腺激素水平也未升高。骨吸收增加可能与破骨细胞溶酶体酶泄漏到骨基质中有关。骨形成逐渐减少，而骨吸收增加持续存在。这导致6个月大时出现严重骨质减少。特征性骨表现可能有助于II型粘脂贮积症的早期诊断，但其发病机制仍有待阐明。
