Re-evaluation of kyphomelic dysplasia

De novo heterozygous variants in KIF5B cause kyphomelic dysplasia

Kyphomelic dysplasia is a heterogeneous group of skeletal dysplasias characterized by severe bowing of the limbs associated with other variable findings, such as narrow thorax and abnormal facies. We searched for the genetic etiology of this disorder. Four individuals diagnosed with kyphomelic dysplasia were enrolled. We performed whole-exome sequencing and evaluated the pathogenicity of the identified variants. All individuals had de novo heterozygous variants in KIF5B encoding kinesin-1 heavy chain: two with c.272A>G:p.(Lys91Arg), one with c.584C>A:p.(Thr195Lys), and the other with c.701G>T:p.(Gly234Val). All variants involved conserved amino acids in or close to the ATPase activity-related motifs in the catalytic motor domain of the KIF5B protein. All individuals had sharp angulation of the femora and humeri, distinctive facial features, and neonatal respiratory distress. Short stature was observed in three individuals. Three developed postnatal osteoporosis with subsequent fractures, two showed brachycephaly, and two were diagnosed with optic atrophy. Our findings suggest that heterozygous KIF5B deleterious variants cause a specific form of kyphomelic dysplasia. Furthermore, alterations in kinesins cause various symptoms known as kinesinopathies, and our findings also extend the phenotypic spectrum of kinesinopathies. This article is protected by copyright. All rights reserved.

Stüve-Wiedemann syndrome and related bent bone dysplasias

Stüve-Wiedemann syndrome (SWS) is a severe congenital skeletal dysplasia associated with life threatening dysautonomic manifestations. Newborns affected with this condition exhibit distinctive shortening and bowing of the long bones with reduced bone volume. The majority of affected newborns die early due to neuromuscular complications namely hyperthermia, apnea, and swallowing difficulties. In this review, we provide an overall picture on the clinical, including long-term management, molecular and cellular aspects of SWS and discuss briefly other related bent bone dysplasias.

Congenital contractures and distinctive phenotypic features consistent with Stuve-Wiedmann syndrome in a male infant

Introduction

Expressionless face associated with multiple contractures has been encountered in an infant. There is a wide range of misconception regarding the categorization of children with multiple contractures among different pediatric disciplines. The fundamental element in categorizing children with multiple contractures is "the etiological understanding". In the absence of concomitant neuromuscular disease, however, the search for other reasons is mandatory. Our present paper signifies the necessity of proper interpretations of unusual clinical and radiographic features.

Case presentation

We describe a 3-months-old-infant presented with the phenotypic and the radiographic features consistent with the diagnosis of Stüve-Wiedemann syndrome. We report what might be the first clinical report of Stüve-Wiedemann syndrome from a consanguineous family in Austria.

Conclusion

Congenital limitations of the hips in a newborn infant raise the possibility of " Congenital Hip Dislocation". As congenital hip dislocation is a dysplastic process. Here further knowledge by the pediatrician and the orthopaedic surgeon is needed. Our present patient appears to constitute a distinct pathological entity consistent with Stüve-Wiedemann syndrome (SWS). Superti-Furga et al, and Cormier-Daire et al, also suggest that Stüve-Wiedemann syndrome and Schwartz-Jampel syndrome type 2 are allelic conditions. We wish to stress that, given the rarity of syndromic malformation complex, our impression is that it is more common than it is reported.

Angulated femurs and the skeletal dysplasias: experience of the International Skeletal Dysplasia Registry (1988-2006)

Angulated or bent femur (isolated or associated with other long bone bowing) in the fetus or newborn is relatively common when evaluating patients with skeletal dysplasias. To determine the extent and heterogeneity of disorders associated with angulated or bent femurs, we analyzed cases in the radiographic database (1998-2006) of the International Skeletal Dysplasia Registry (ISDR) and determined which established skeletal dysplasias and genetic syndromes are associated with this finding. The results show that more than 40 distinct disorders with varying frequency (very rare to more commonly occurring disorders) can be associated with bowed/bent/angulated femurs. Sixty-six percent of the cases with angulated femurs belonged to three well described groups of disorders; campomelic disorders (24.4%), thanatophoric dysplasia (23.9%) and osteogenesis imperfecta (OI) (18.1%). With specific emphasis on these, this cross-sectional cohort provides discussion of data on other rare disorders associated with angulated femurs and the importance of the finding relative to its occurrence within a diagnostic group. This study aims to provide differential diagnosis of entities to be considered when a fetus or newborn is found to have congenital bowing/angulation of the femur.

New insights in congenital bowing of the femora

The aim of this study is to review the clinical, radiological and molecular findings of the bent bone dysplasia group including Stüve-Wiedemann syndrome due to LIFR mutations, Compomelic dysplasia due to SOX9 mutations and Kyphomelic dysplasia with no known molecular bases.