EVEN-PLUS syndrome: A case report with novel variants in HSPA9 and evidence of HSPA9 gene dysfunction

Prenatal to preimplantation genetic diagnosis of a novel compound heterozygous mutation in HSPA9 associated with Even-Plus syndrome

BACKGROUND

Heat shock protein family A member 9 (HSPA9) prevents unfolded and dysfunctional protein accumulation, with genetic variants known to be pathogenic. Here, we determined the genetic cause of Even-Plus syndrome (OMIM: 616854) in a Chinese family.

METHODS

We collected samples from two affected and two normal individuals. Whole-exome sequencing was performed to identify their genetic profiles. Potential variants were validated using Sanger sequencing. Assisted reproduction with mutation-free embryos successfully blocked the transmission of mutations.

RESULTS

We identified novel inherited pathogenic complex heterozygous variations in the HSPA9 gene in the two affected fetuses. Three-dimensional spatial simulation of the HSPA9 protein after prediction of the mutated RNA splicing pattern abolished part of the substrate-binding domain of the protein. According to ACMG guidelines, c. 1822-1G>A and c. 1411-3T>G were classified as pathogenic and likely pathogenic, respectively. Mutation-free embryos were selected for transplantation and reconfirmed to possess no mutations. A healthy daughter was successfully born into the family.

CONCLUSIONS

This study is the first to report complex heterozygous variations in the HSPA9 gene that influence alternative splicing in early pregnancy. Our findings expand on the mutational spectrum leading to Even-Plus syndrome and provide a basis for genetic counseling and future embryonic studies.

A new phenotype of EVEN-PLUS syndrome in a Chinese family and literature review

BACKGROUND

Epiphyseal, Vertebral, Ear, and Nose (EVEN)-PLUS syndrome is a rare condition characterized by the involvement of the Epiphyses, Vertebrae, Ears, and Nose, plus other associated findings, due to pathogenic variants in the HSPA9 gene. Due to the sparse number of patients, the clinical phenotypic spectrum is not clear.

METHODS

We report two patients with pathogenic HSPA9 variants from a Chinese family. Besides the core clinical features of EVEN-PLUS syndrome, the two cases had seizures, developmental delay, and basal ganglia lesions in cerebral MRI. We also reviewed the previously published reports of patients with biallelic pathogenic HSPA9 variants.

RESULTS

Together with the presented cases, 12 cases (9 females) were identified from 6 relevant research items for analysis. All patients had synophrys or arched eyebrows, hypoplastic or dysplastic ears, hypoplastic nasal bone, and dysplastic femoral head. Other specific craniofacial features (such as triangular nares), abnormal skeletal presentations (such as bifid femur, dysplastic epiphyses at the knee, dysplastic acetabula, delayed ossification, short stature, vertebral clefting, scoliosis, and dislocated patellae), congenital heart defects, and renal alterations are common clinical features. Two patients had seizures and basal ganglia lesions in cerebral MRI. Infrequent features, such as aplasia cutis, short thorax and sternum, and widely spaced nipples, are also observed in the syndrome. Thirteen variants associated with EVEN-PLUS syndrome have been reported.

CONCLUSIONS

HSPA9 gene mutations should be suspected in all cases with specific craniofacial features, abnormal skeletal presentations, congenital heart defects, and renal alterations. Seizures and basal ganglia lesions are a new phenotype of EVEN-PLUS syndrome.

Genetics of non-isolated hemivertebra: A systematic review of fetal, neonatal, and infant cases

Hemivertebra is a congenital vertebral malformation caused by unilateral failure of formation during embryogenesis that may be associated with additional abnormalities. A systematic review was conducted to investigate genetic etiologies of non-isolated hemivertebra identified in the fetal, neonatal, and infant periods using PubMed, Cochrane database, Ovid Medline, and ClinicalTrials.gov from inception through May 2022 (PROSPERO ID CRD42021229576). The Human Phenotype Ontology database was accessed May 2022. Studies were deemed eligible for inclusion if they addressed non-isolated hemivertebra or genetic causes of non-isolated hemivertebra identified in the fetal, neonatal, or infant periods. Cases diagnosed clinically without molecular confirmation were included. Systematic review identified 23 cases of non-isolated hemivertebra with karyotypic abnormalities, 2 cases due to microdeletions, 59 cases attributed to single gene disorders, 18 syndromic cases without known genetic etiology, and 14 cases without a known syndromic association. The Human Phenotype Ontology search identified 49 genes associated with hemivertebra. Non-isolated hemivertebra is associated with a diverse spectrum of cytogenetic abnormalities and single gene disorders. Genetic syndromes were notably common. Frequently affected organ systems include musculoskeletal, cardiovascular, central nervous system, genitourinary, gastrointestinal, and facial dysmorphisms. When non-isolated hemivertebra is identified on prenatal ultrasound, the fetus must be assessed for associated anomalies and genetic counseling is recommended.

Identifying patients with EVEN-plus syndrome using exome sequencing and clinical feature analysis: A case report

BACKGROUND

The EVEN-plus syndrome (epiphyseal-vertebral-ear-nose dysplasia plus associated findings) is an extremely rare autosomal recessive inherited disease characterised by specific facial features and skeletal dysplasia. It has a prenatal onset due to defects in the HSPA9 gene. The syndrome has not been reported previously in China.

METHODS

This study reported the characteristics, examination results, diagnosis and treatment of a female case aged 3 years and 3 months.

RESULTS

The patient had global developmental delay and specific facial features, including a prominent forehead, a bilateral auricle deformity, a collapsed nose, a high palatine arch, a short neck and other appearance abnormalities. Her hip joint magnetic resonance imaging (MRI) results showed bilateral femoral head epiphyseal dysplasia with a fork-shaped malformation at the distal end, and her brain MRI showed white matter myelin dysplasia. HSPA9 compound heterozygous variants c.882_c.883delAG and c.613A>G were identified by exome sequencing.

CONCLUSIONS

This finding expands the spectra of EVEN-plus syndrome phenotype and pathogenic variants and suggests that c.882_c.883delAG may have a higher distribution frequency in East Asian populations.

Broadening the phenotypic spectrum of EVEN-PLUS syndrome through identification of HSPA9 pathogenic variants in the original EVE dysplasia family and two sibs with milder facial phenotype

EVEN-PLUS syndrome is a rare autosomal recessive disorder caused by biallelic pathogenic variants in the mitochondrial chaperone called mortalin, encoded by HSPA9. This genetic disorder, presenting with several overlapping features with CODAS syndrome, is characterized by the involvement of the Epiphyses, Vertebrae, Ears, and Nose (EVEN), PLUS associated findings. Only five individuals presenting with the EVEN-PLUS phenotype and biallelic variants in HSPA9 have been published. Here, we expand the phenotypic and molecular spectrum associated with this disorder, reporting two sibs with a milder phenotype and compound heterozygous pathogenic variants (a recurrent variant and a novel one). Also, we confirm a homozygous pathogenic variant in the family originally reported as EVE dysplasia.

Skeletal Phenotypes Due to Abnormalities in Mitochondrial Protein Homeostasis and Import

Mitochondrial disease represents a collection of rare genetic disorders caused by mitochondrial dysfunction. These disorders can be quite complex and heterogeneous, and it is recognized that mitochondrial disease can affect any tissue at any age. The reasons for this variability are not well understood. In this review, we develop and expand a subset of mitochondrial diseases including predominantly skeletal phenotypes. Understanding how impairment ofdiverse mitochondrial functions leads to a skeletal phenotype will help diagnose and treat patients with mitochondrial disease and provide additional insight into the growing list of human pathologies associated with mitochondrial dysfunction. The underlying disease genes encode factors involved in various aspects of mitochondrial protein homeostasis, including proteases and chaperones, mitochondrial protein import machinery, mediators of inner mitochondrial membrane lipid homeostasis, and aminoacylation of mitochondrial tRNAs required for translation. We further discuss a complex of frequently associated phenotypes (short stature, cataracts, and cardiomyopathy) potentially explained by alterations to steroidogenesis, a process regulated by mitochondria. Together, these observations provide novel insight into the consequences of impaired mitochondrial protein homeostasis.