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Orthopaedic Surgery Feb 2020Metatropic dysplasia (MD), is a rare skeletal dysplasia occurring predominantly in infants characterized by a distinctive long torso and short limbs; it is as a result...
Metatropic dysplasia (MD), is a rare skeletal dysplasia occurring predominantly in infants characterized by a distinctive long torso and short limbs; it is as a result of mutations in the TRPV4 gene. However, a clear distinction between various forms of skeletal dysplasias caused by the transient receptor potential vanilloid 4 (TRPV4) gene is difficult but could be achieved by a combination of gene sequencing, medical and radiological criteria. We hereby report a case of a 14-month old girl who presented with an abnormal stature. The diagnosis of nonlethal MD was confirmed by X-ray with dumbbell-shaped long bones, platyspondyly, and delayed carpal ossification, as well as broadened pelvis with marginally widened ilia, epiphyseal plates, and slightly flattened acetabula. Furthermore, gene sequencing confirmed gene mutation on exon 15 of the TRPV4 gene with a heterozygous missense mutation (c.2396C > T), but no mutation was present in her parents. Our findings recorded metatropic dysplasia with the c.2396C > T mutation in the TRPV4 gene in China. This mutation caused changes in amino acid of TRPV4, which can induce growth retardation in children.
Topics: Asian People; China; Dwarfism; Female; Humans; Infant; Osteochondrodysplasias; Radiography
PubMed: 31808622
DOI: 10.1111/os.12546 -
Biochemistry and Biophysics Reports Sep 2019Metatropic dysplasia is a congenital skeletal dysplasia characterized by severe platyspondyly, dumbbell-like deformity of long tubular bones, and progressive...
Metatropic dysplasia is a congenital skeletal dysplasia characterized by severe platyspondyly, dumbbell-like deformity of long tubular bones, and progressive kyphoscoliosis with growth. It is caused by mutations in the gene , encoding the transient receptor potential vanilloid 4, which acts as a calcium channel. Many heterozygous single base mutations of this gene have been associated with the disorder, showing autosomal dominant inheritance. Although abnormal endochondral ossification has been observed by histological examination of bone in a patient with lethal metatropic dysplasia, the etiology of the disorder remains largely unresolved. As dental pulp stem cells (DPSCs) are mesenchymal stem cells that differentiate into bone lineage cells, DPSCs derived from patients with congenital skeletal dysplasia might be useful as a disease-specific cellular model for etiological investigation. The purpose of this study was to clarify the pathological association between mutation and chondrocyte differentiation by analyzing DPSCs from a patient with non-lethal metatropic dysplasia. We identified a novel heterozygous single base mutation, c.1855C>T in . This was predicted to be a missense mutation, p.L619F, in putative transmembrane segment 5. The mutation was repaired by CRISPR/Cas9 system to obtain isogenic control DPSCs for further analysis. The expression of stem cell markers and fibroblast-like morphology were comparable between patient-derived mutant and control DPSCs, although expression of TRPV4 was lower in mutant DPSCs than control DPSCs. Despite the lower TRPV4 expression in mutant DPSCs, the intracellular Ca level was comparable at the basal level between mutant and control DPSCs, while its level was markedly higher following stimulation with 4α-phorbol 12,13-didecanoate (4αPDD), a specific agonist for TRPV4, in mutant DPSCs than in control DPSCs. In the presence of 4αPDD, we observed accelerated early chondrocyte differentiation and upregulated mRNA expression of SRY-box 9 () in mutant DPSCs. Our findings suggested that the novel missense mutation c.1855C>T of was a gain-of-function mutation leading to enhanced intracellular Ca level, which was associated with accelerated chondrocyte differentiation and upregulation. Our results also suggest that patient-derived DPSCs can be a useful disease-specific cellular model for elucidating the pathological mechanism of metatropic dysplasia.
PubMed: 31463371
DOI: 10.1016/j.bbrep.2019.100648