Department of Pediatrics, the Second Xiangya Hospital, Central South University, Changsha, 410011, Hunan, China.
BMC Nephrol. 2020 May 11;21(1):170. doi: 10.1186/s12882-020-01809-6.
Schimke immuno-osseous dysplasia (SIOD) is a rare autosomal recessive disorder characterized by spondyloepiphyseal dysplasia, progressive renal insufficiency and defective cellular immunity. Podocytic infolding glomerulopathy (PIG) is a newly proposed disease entity characterized by microspheres or microtubular structures associated with podocytes infolding into the glomerular basement membrane (GBM) on electron microscopy (EM).
A 4-year-old boy was admitted to our ward due to proteinuria and edema lasting 1 month. He had a short trunk and demonstrated subtle dysmorphology, with a triangular shape, a broad nasal bridge and a bulbous nasal tip. The laboratory findings were as follows: lymphocytes, 0.5 × 10/L; urine protein, 3.67 g/d; albumin, 9.8 g/L; and cholesterol, 11.72 mmol/L. Skeletal X rays showed small iliac wings, small ossification centers of the capital femoral epiphyses, shallow dysplastic acetabular fossae and mildly flattened vertebrae. The specimen for light microscopy (LM) suggested focal segmental glomerulosclerosis (FSGS). EM revealed a focal thickness of the GBM with some cytoplasmic processes of podocyte infolding into the GBM. Gene sequencing showed novel compound heterozygous mutations in the SMARCAL1 gene (c.2141 + 5G > A; c.2528 + 1G > A) that were inherited from his parents. Finally, we established the diagnosis of SIOD and treated him with diuretics and angiotensin-converting enzyme inhibitors (ACEIs).
The pathogenic mechanism of PIG has not been clarified. Further studies are required to understand whether gene mutations, especially those related to podocytes, contribute to the pathogenesis of podocytic infolding.
Schimke 免疫骨发育不良（SIOD）是一种罕见的常染色体隐性遗传病，其特征为脊椎骨骺发育不良、进行性肾功能不全和细胞免疫缺陷。足细胞内褶肾小球病（PIG）是一种新提出的疾病实体，其特征为电子显微镜下与足细胞内褶到肾小球基底膜（GBM）相关的微球体或微管结构。
一名 4 岁男孩因蛋白尿和水肿持续 1 个月而入院。他身材矮小，表现出细微的畸形，呈三角形，鼻梁宽，鼻尖呈球状。实验室检查结果如下：淋巴细胞 0.5×10/L；尿蛋白 3.67 g/d；白蛋白 9.8 g/L；胆固醇 11.72 mmol/L。骨骼 X 射线显示髂骨翼小，股骨头骨骺中心小，髋臼窝浅发育不良，椎体轻度扁平。光镜（LM）标本提示局灶节段性肾小球硬化（FSGS）。电子显微镜显示 GBM 局灶性增厚，一些足细胞的细胞质突起内褶到 GBM。基因测序显示 SMARCAL1 基因的新型复合杂合突变（c.2141+5G>A；c.2528+1G>A），来自其父母的遗传。最终，我们诊断为 SIOD，并给予利尿剂和血管紧张素转换酶抑制剂（ACEIs）治疗。
PIG 的发病机制尚不清楚。需要进一步研究以了解基因突变，特别是与足细胞相关的基因突变是否有助于足细胞内褶的发病机制。
