Metatropic Dysplasia (TRPV4): Mechanistic Summary
Genetics and inheritance
Metatropic dysplasia is caused by heterozygous activating variants in TRPV4 and is primarily autosomal dominant. Both nonlethal and lethal forms are reported within the same dominant framework (PMID:20425821). De novo heterozygous variants are frequent in sporadic cases (PMID:19232556).
Pathophysiology
TRPV4 encodes a calcium-permeable ion channel. Disease-associated variants increase channel activity and are linked to elevated chondrocyte calcium signaling (PMID:20425821; PMID:19232556). Histologic data in lethal cases demonstrate markedly disrupted endochondral ossification and altered growth plate chondrocyte differentiation, linking channel hyperactivity to skeletal maldevelopment (PMID:20425821).
Hallmark phenotype profile
Key features include: - short stature and short extremities - progressive kyphoscoliosis - platyspondyly - severe metaphyseal involvement with widened metaphyses - dumbbell-shaped long bones
These features are captured across cohort and spectrum studies in TRPV4-related skeletal dysplasia families (PMID:21658220; PMID:20425821).
Disease spectrum context
Metatropic dysplasia is part of a TRPV4 skeletal dysplasia continuum with spondylometaphyseal dysplasia, Kozlowski type, and brachyolmia, with overlap and variable severity across families (PMID:19232556; PMID:21658220).