Attenuated Type of Asphyxiating Thoracic Dysplasia due to Mutations in DYNC2H1 Gene.

Anna Čechová,Markéta Tesařová,Jiří Zeman,Václav Čunát,Alice Baxová,Lukáš Lambert,Alena Leiská,Tomáš Honzík

doi:10.14712/23362936.2019.17

Abstract

Asphyxiating thoracic dysplasia (ATD) represents a heterogeneous group of skeletal dysplasias with short ribs, narrow chest and reduced thoracic capacity. Mutations in several genes including IFT80, DYNC2H1, TTC21B and WDR19 have been found in patients with ATD. Both severe and milder course of the disease were described in correlation with secondary involvement of lung's function. Two children with attenuated form of ATD are described. Their anthropometric parameters for birth weight, length and head circumference were normal but narrow thorax was observed in both of them in early infancy with chest circumference < -3 SD (standard deviation) in comparison to age related controls. The postnatal adaptation and development of both children was uneventful except for mild tachypnoea in one of them which persisted till the age of 6 months. In both children, radiographs revealed narrow upper half of the chest with shorter ribs and atypical configuration of pelvis with horizontally running acetabula and coarse internal edges typical for ATD. Molecular analyses using whole exome sequencing in one family revealed that the patient is compound heterozygote in DYNC2H1 gene for a frame-shift mutation c.4458delT resulting in premature stop-codon p.Phe1486Leufs*11 and a missense mutation c.9044A>G (p.Asp3015Gly). The second family refused the DNA analysis. Regular monitoring of anthropometric parameters during childhood is of big importance both in health and disease. In addition, measurement of the chest circumference should be included, at least at birth and during infancy.

Highlights

Asphyxiating thoracic dysplasia (ATD, Jeune syndrome) is a rare skeletal disease belonging to the large group of ciliopathies, disorders with primary impairment of cilia involved in the transduction of signals in the hedgehog pathway that is especially important in skeletal development (Dagoneau et al, 2009; Huber and CormierDaire, 2012)
ATD is characterized by short ribs resulting in narrow chest and reduced thoracic capacity, short long bones, inconstant polydactyly, and trident acetabular roof sometimes accompanied by renal, liver and retinal disease (Dagoneau et al, 2009)
We report the results of clinical and radiologic analyses in two children with attenuated type of asphyxiating thoracic dysplasia, in one of them due to mutations in DYNC2H1

Summary

Introduction

Asphyxiating thoracic dysplasia (ATD, Jeune syndrome) is a rare skeletal disease belonging to the large group of ciliopathies, disorders with primary impairment of cilia involved in the transduction of signals in the hedgehog pathway that is especially important in skeletal development (Dagoneau et al, 2009; Huber and CormierDaire, 2012). The course of the disease and the prognosis depend on the severity of ribs shortening with the residual lung function, recurrent lung infections and secondary heart problems (Emiralioglu et al, 2018). Both severe and attenuated forms of ATD were described, but the phenotype may differ even between siblings with the identical mutation in DYNC2H1 suggesting the impact of some modifier alleles or epigenetic factors (Schmidts et al, 2013a). We report the results of clinical and radiologic analyses in two children with attenuated type of asphyxiating thoracic dysplasia, in one of them due to mutations in DYNC2H1

Methods

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Discussion