Craniofacial and Craniocervical Features in Cartilage-Hair Hypoplasia: A Radiological Study of 17 Patients and 34 Controls.

Marjut Evälahti,Outi Mäkitie,Heidi Arponen

doi:10.3389/fendo.2021.741548

Marjut Evälahti, Outi Mäkitie + Show 1 more

Open Access

https://doi.org/10.3389/fendo.2021.741548

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Abstract

BackgroundBiallelic mutations in the non-coding RNA gene RMRP cause Cartilage-hair hypoplasia (CHH), a rare skeletal dysplasia in which the main phenotypic characteristic is severe progressive growth retardation.ObjectiveThis study compared the cranial dimensions of individuals with CHH to healthy subjects.MethodsLateral skull radiographs of 17 patients with CHH (age range 10 to 59 years) and 34 healthy individuals (age range 10 to 54 years) were analyzed for relative position of the jaws to skull base, craniofacial height and depth, as well as vertical growth pattern of the lower jaw, anterior cranial base angle, and the relationship between the cervical spine and skull base.ResultsWe found that the length of the upper and lower jaws, and clivus were significantly decreased in patients with CHH as compared to the controls. Anterior cranial base angle was large in patients with CHH. Basilar invagination was not found.ConclusionThis study found no severe craniofacial involvement of patients with CHH, except for the short jaws. Unexpectedly, mandibular deficiency did not lead to skeletal class II malocclusion.Clinical ImpactAlthough the jaws were shorter in patients with CHH, they were proportional to each other. A short posterior cranial base was not associated with craniocervical junction pathology.

Highlights

Cartilage-hair hypoplasia (CHH) is a rare autosomal recessive chondrodysplasia caused by mutations in the untranslated RMRP gene on chromosome 9p13-p12 encoding the RNA component of a mitochondrial ribonuclease complex [1]
Radiographs of 17 patients (5 males, 12 females) diagnosed with CHH were included in the study
Two of the control images were of growing individuals age- and gendermatched with the child with CHH

Summary

Introduction

Cartilage-hair hypoplasia (CHH) is a rare autosomal recessive chondrodysplasia caused by mutations in the untranslated RMRP gene on chromosome 9p13-p12 encoding the RNA component of a mitochondrial ribonuclease complex [1]. It affects bone metaphyses and leads to progressive growth disturbance and severe short-limbed short stature [2]. CHH is exceptionally prevalent in Finland and among the North American Amishpopulation [2, 6]. Biallelic mutations in the non-coding RNA gene RMRP cause Cartilage-hair hypoplasia (CHH), a rare skeletal dysplasia in which the main phenotypic characteristic is severe progressive growth retardation

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