GDF5 mutation case report and a systematic review of molecular and clinical spectrum: Expanding current knowledge on genotype-phenotype correlations

A missense GDF5 variant causes brachydactyly type A1 and multiple-synostoses syndrome 2

Objective

This study aimed to identify the molecular defects and clinical manifestations in a Chinese family with brachydactyly (BD) type A1 (BDA1) and multiple-synostoses syndrome 2 (SYNS2).

Methods

A Chinese family with BDA1 and SYNS2 was enrolled in this study. Whole-exome sequencing was used to analyze the gene variants in the proband. The sequences of the candidate pathogenic variant in GDF5 was validated via Sanger sequencing. I-TASSER and PyMOL were used to analyze the functional domains of the corresponding mutant proteins.

Results

The family was found to have an autosomal-dominantly inherited combination of BDA1 and SYNS2 caused by the S475N variant in the GDF5 gene. The variant was located within the functional region, and the mutated residue was found to be highly conserved among species. Via bioinformatic analyses, we predicted this variant to be deleterious, which perturb the protein function. The substitution of the negatively charged amino acid S475 with the neutral N475 was predicted to disrupt the formation of salt bridges with Y487 and impair the structure, stability, and function of the protein, consequently, the abnormalities in cartilage and bone development ensue.

Conclusions

A single genetic variant (S475N) which disrupt the formation of salt bridges with Y487, in the interface of the antagonist- and receptor-binding sites of GDF5 concurrently causes two pathological mechanisms. This is the first report of this variant, identified in a Chinese family with BDA1 and SYNS2.

Frameshift Mutation in a Chinese Patient with Brachydactyly Type C Involving the Third Metacarpal: A Case Report

Brachydactyly is a common feature of congenital hand anomalies characterized by shortening of the phalanges and/or metacarpals. Mutation of growth differentiation factor‐5 (GDF5) may result in loss of appearance and function in brachydactyly type C (BDC). Herein, we describe an 11 year‐old Chinese BDC patient with significant shortening of the 1st, 2nd, 3rd, and 5th digits. Notably, according to the analysis of metacarpophalangeal pattern profiles, we do not think the 4th digit appears unaffected as usual. In this patient a novel heterozygous frameshift mutation was identified (c.349delG) causing termination of translation after translating six amino acids from codon 117 (p.A117fs*6). This mutation is located in the propeptide region of GDF5, causing GDF5 haploinsufficiency in BDC. Considering our results expanding the genetic spectrum of BDC‐causing mutations, further molecular analysis to diagnose and reclassify isolated brachydactyly on the basis of genotype rather than phenotype is warranted.

Current Insights Into the Maintenance of Structure and Function of Intervertebral Disc: A Review of the Regulatory Role of Growth and Differentiation Factor-5

Intervertebral disc degeneration (IDD), characterized by conversion of genotypic and phenotypic, is a major etiology of low back pain and disability. In general, this process starts with alteration of metabolic homeostasis leading to ongoing inflammatory process, extracellular matrix degradation and fibrosis, diminished tissue hydration, and impaired structural and mechanical functionality. During the past decades, extensive studies have focused on elucidating the molecular mechanisms of degeneration and shed light on the protective roles of various factors that may have the ability to halt and even reverse the IDD. Mutations of GDF-5 are associated with several human and animal diseases that are characterized by skeletal deformity such as short digits and short limbs. Growth and differentiation factor-5 (GDF-5) has been shown to be a promise biological therapy for IDD. Substantial literature has revealed that GDF-5 can decelerate the progression of IDD on the molecular, cellular, and organ level by altering prolonged imbalance between anabolism and catabolism. GDF family members are the central signaling moleculars in homeostasis of IVD and upregulation of their gene promotes the expression of healthy nucleus pulposus (NP) cell marker genes. In addition, GDF signaling is able to induce mesenchymal stem cells (MSCs) to differentiate into NPCs and mobilize resident cell populations as chemotactic signals. This review will discuss the promising critical role of GDF-5 in maintenance of structure and function of IVDs, and its therapeutic role in IDD endogenous repair.

The effect of common variants in GDF5 gene on the susceptibility to chronic postsurgical pain

Background

The growth differentiation factor 5 (GDF5) gene regulates the growth of neuronal axons and dendrites and plays a role in the inflammatory response and tissue damage. The gene may also be associated with chronic postsurgical pain. This study aimed to reveal the relationship between SNPs in the GDF5 gene and orthopedic chronic postsurgical pain in Han Chinese population based on a case-control study.

Methods

We genotyped 8 SNPs within GDF5 gene in 1048 surgical patients with chronic postsurgical pain as the case group and 2062 surgical patients who were pain free as the control group. SNP and haplotypic analyses were performed, and stratified analyses were conducted to determine the correlations between significant SNPs and clinical characteristics.

Results

Only rs143384 in the 5′UTR of GDF5 was identified as significantly associated with increased susceptibility to chronic postsurgical pain, and the risk of A allele carriers was increased approximately 1.35-fold compared with that of G allele carriers. Haplotypes AGG and GGG in the LD block rs143384-rs224335-rs739329 also showed similar association patterns. Furthermore, we found that rs143384 was significantly correlated with chronic postsurgical pain in the subgroup aged ≤ 61 years, subgroup with a BMI ≤ 26, subgroup with no-smoking or no pain history, and subgroup with a drinking history.

Conclusion

Our study provided supportive evidence that genetic variations in the GDF5 gene are potential genetic factors that can increase the risk of chronic postsurgical pain in the Han Chinese population, but further research is necessary to elucidate the underlying mechanism.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02549-5.

Whole Exome Sequencing Reveals a Novel AUTS2 In-Frame Deletion in a Boy with Global Developmental Delay, Absent Speech, Dysmorphic Features, and Cerebral Anomalies

Neurodevelopmental disorders (NDDs) are a group of highly prevalent, clinically and genetically heterogeneous pediatric disorders comprising, according to the Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-V), intellectual disability, developmental delay, autism spectrum disorders, and other neurological and cognitive disorders manifesting in the developmental age. To date, more than 1000 genes have been implicated in the etiopathogenesis of NNDs. Among them, AUTS2 (OMIM # 607270) encodes a protein involved in neural migration and neuritogenesis, and causes NNDs with different molecular mechanisms including copy number variations, single or multiple exonic deletion and single nucleotide variants. We describes a 9-year-old boy with global developmental delay, absent speech, minor craniofacial anomalies, hypoplasia of the cerebellar vermis and thinning of the corpus callosum, resulted carrier of the de novo AUTS2 c.1603_1626del deletion at whole exome sequencing (WES) predicted to cause the loss of eight amino acids [p.(His535_Thr542del)]. Notably, our patient is the first reported so far in medical literature carrying an in-frame deletion and the first in which absent language, hypoplasia of the cerebellar vermis and thinning of the corpus callosum has been observed thus useful to expand the molecular spectrum of AUTS2 pathogenic variants and to broaden our knowledge on the clinical phenotype associated.