biostudies-literatureObiezu FIntramural NIH HHSNCATS NIH HHSNIDDK NIH HHSziae156https://www.ebi.ac.uk/biostudies/studies/S-EPMC11736719biostudies-literatureUnknown9(2)Jansen metaphyseal chondrodysplasia (JMC) is an ultra-rare disorder caused by constitutive activation of parathyroid hormone type 1 receptor (PTH1R). We sought to characterize the craniofacial phenotype of patients with the disease. Six patients with genetically confirmed JMC underwent comprehensive craniofacial phenotyping revealing a distinct facial appearance that prompted a cephalometric analysis demonstrating a pattern of mandibular retrognathia. Oral examination was notable for flat and shallow palate, delayed eruption pattern, and impacted maxillary teeth. Subclinical and/or mild hearing loss was noted in 4 of 5 patients studied. The most common etiology was conductive, likely due to overcrowding of epitympanum which impedes the normal vibration of ossicles to sound. Paranasal sinusJBMR plusJansen metaphyseal chondrodysplasia: analysis of craniofacial manifestations.PMC11736719ZIA DK043006R01 DK113039ZIA DC000064ZIA HG200407KL2 TR000425Obiezu FKim HJFerreira CRGafni RILee JSCollins MTBoyce AChu EJha SAlmpani KZalewski CFarhadi FRoszko KLJahanmir GWeinstein LSJuppner HfalseJansen metaphyseal chondrodysplasia: analysis of craniofacial manifestations.Jansen metaphyseal chondrodysplasia (JMC) is an ultra-rare disorder caused by constitutive activation of parathyroid hormone type 1 receptor (PTH1R). We sought to characterize the craniofacial phenotype of patients with the disease. Six patients with genetically confirmed JMC underwent comprehensive craniofacial phenotyping revealing a distinct facial appearance that prompted a cephalometric analysis demonstrating a pattern of mandibular retrognathia. Oral examination was notable for flat and shallow palate, delayed eruption pattern, and impacted maxillary teeth. Subclinical and/or mild hearing loss was noted in 4 of 5 patients studied. The most common etiology was conductive, likely due to overcrowding of epitympanum which impedes the normal vibration of ossicles to sound. Paranasal sinus2025-01-01T00:00:00Z2025 Feb2026-06-05T18:00:12.065Z2026-05-20T03:09:33.096ZS-EPMC117367193983014910.1093/jbmrpl/ziae156