Molecular Mechanisms of Craniofacial and Dental Abnormalities in Osteopetrosis

ADAM19 cleaves the PTH receptor and associates with brachydactyly type E

Brachydactyly type E (BDE), shortened metacarpals, metatarsals, cone-shaped epiphyses, and short stature commonly occurs as a sole phenotype. Parathyroid hormone-like protein (PTHrP) has been shown to be responsible in all forms to date, either directly or indirectly. We used linkage and then whole genome sequencing in a small pedigree, to elucidate BDE and identified a truncated disintegrin-and-metalloproteinase-19 (ADAM19) allele in all affected family members, but not in nonaffected persons. Since we had shown earlier that the extracellular domain of the parathyroid hormone receptor (PTHR1) is subject to an unidentified metalloproteinase cleavage, we tested the hypothesis that ADAM19 is a sheddase for PTHR1. WT ADAM19 cleaved PTHR1, while mutated ADAM-19 did not. We mapped the cleavage site that we verified with mass spectrometry between amino acids 64-65. ADAM-19 cleavage increased Gq and decreased Gs activation. Moreover, perturbed PTHR1 cleavage by ADAM19 increased ß-arrestin2 recruitment, while cAMP accumulation was not altered. We suggest that ADAM19 serves as a regulatory element for PTHR1 and could be responsible for BDE. This sheddase may affect other PTHrP or PTH-related functions.

Craniofacial disorders and dysplasias: Molecular, clinical, and management perspectives

There is a wide spectrum of craniofacial bone disorders and dysplasias because embryological development of the craniofacial region is complex. Classification of craniofacial bone disorders and dysplasias is also complex because they exhibit complex clinical, pathological, and molecular heterogeneity. Most craniofacial disorders and dysplasias are rare but they present an array of phenotypes that functionally impact the orofacial complex. Management of craniofacial disorders is a multidisciplinary approach that involves the collaborative efforts of multiple professionals. This review provides an overview of the complexity of craniofacial disorders and dysplasias from molecular, clinical, and management perspectives.

Maxillary osteomyelitis in a young female with osteopetrosis: unveiling an uncommon connection

Osteopetrosis encompasses a spectrum of conditions marked by heightened bone density due to faulty osteoclast-mediated bone resorption, leading to an accumulation of immature bone and thickened cortical structures. This condition gives rise to bone fragility, blood cell irregularities, nerve entrapment and growth challenges, all stemming from disrupted bone remodelling. Craniofacial distinctiveness, encompassing anomalies in the skull and jaw, is a frequent occurrence. Osteopetrosis presents a range of clinical signs, including facial and dental anomalies. The diagnostic process involves thorough clinical and radiological assessments, often obviating the need for genetic testing. Interestingly, few prior reports have delved into the specifics of craniofacial and dental issues in osteopetrosis. The presented case showcases rare occurrence of maxillary osteomyelitis. The diagnosis was established through a combination of history, clinical, radiographic and laboratory findings. The patient declined surgical intervention, leading to the implementation of conservative management involving regular irrigation alongside systemic antibiotic therapy.