Molecular Genetics & Genomic Medicine最新文献

Background: Hereditary diffuse gastric cancer (HDGC) (OMIM# 137215) is an autosomal dominant cancer syndrome associated with CDH1 (OMIM# 192090) mutations. Prophylactic total gastrectomy (PTG) is the most recommended preventive treatment when a pathogenic mutation is found. However, the increasing use of genetic testing has led to the identification of incidental CDH1 mutations in individuals without a family history of gastric cancer. It remains unclear whether these patients should undergo prophylactic total gastrectomy.

Methods: Germline DNA, obtained from peripheral blood, was analysed by NGS.

Results: A 47-year-old woman was diagnosed with high-grade serous ovarian carcinoma, FIGO stage IIIC, with a Homologous Recombination Deficiency (HRD) GIS status of 78 (positive, cut-off: 43). She received chemotherapy and niraparib treatment. A multigene panel test revealed no pathogenic mutations in BRCA1 (OMIM# 113705)/BRCA2 (OMIM# 600185) genes, but a de novo deletion of exon 16 in CDH1 was found incidentally. She had no previous family history of gastric or breast cancer. The patient was enrolled in a surveillance program involving periodic endoscopy and was diagnosed with diffuse gastric cancer through biopsies of a pale area in the antrum after 1 year of close endoscopic follow-up.

Conclusion: This case presents supportive evidence for the pathogenic classification of the loss of the last exon of CDH1.

Background: Synonymous variants are non-pathogenic due to non-substitution of amino acids. However, synonymous exonic terminal nucleotide substitutions may affect splicing. Splicing variants are easily analyzed at RNA level for genes expressed in blood cells. Minigene analysis provides another method for splicing variant analysis of genes that are poorly or not expressed in peripheral blood.

Methods: Whole exome sequencing was performed to screen for potential pathogenic mutations in the proband, which were validated within the family by Sanger sequencing. The pathogenicity of the synonymous mutation was analyzed using the minigene technology.

Results: The proband harbored the compound heterogeneous variants c. [291G >A; 572-50C >T] and c.681 + 1G >T in F7, of which the synonymous variant c.291G >A was located at the terminal position of exon 3. Minigene analysis revealed exon3 skipping due to this mutation, which may have subsequently affected protein sequence, structure, and function.

Conclusion: Our finding confirmed the pathogenicity of c.291G >A, thus extending the pathogenic mutation spectrum of F7, and providing insights for effective reproductive counseling.

Background: Autosomal recessive spastic ataxia ofCharlevoix-Saguenay (ARSACS) is a rare neurodegenerative disorder characterizedby early-onset cerebellar ataxia, peripheral sensorimotor neuropathy, and lowerlimb spasticity. We present clinical andgenetic data of the first Bulgarian patients diagnosed with ARSACS by wholeexome sequencing (WES).

Methods: Variant filtering was performed usinglocally established pipeline and the selected variants were analysed by Sangersequencing. All patients underwent clinical examination and testingincluding the standard rating scales for spastic paraplegia and ataxia.

Results: Five different SACS gene variants, three of which novel, have been identified inpatients from three different ethnic groups. In addition to the classicalclinical triad, brain MRI revealed cerebellar atrophy, linear pontineT2-hypointensities, and hyperintense rim lateral tothalamus combined with retinal nerve fiber layer thickening on opticcoherence tomography (OCT).

Conclusion: We expand the mutation, geographic, and phenotypic spectrum of ARSACS, adding Bulgaria to the world map of the disease, and drawing attention to the fact that it is still misdiagnosed. We demonstrated that brain MRI and OCT are necessary clinical tests for ARSACS diagnosis, even if one of the cardinal clinical features is lacking.

Background: Deafness autosomal dominant 2A (DFNA2A) is related to non-syndromic genetic hearing impairment. The KCNQ4 (Potassium Voltage-Gated Channel Subfamily Q Member 4) can lead to DFNA2A. In this study, we report a case of autosomal dominant non-syndromic hearing loss with six family members as caused by a novel variant in the KCNQ4 gene.

Methods: The whole-exome sequencing (WES) and pure tone audiometry were performed on the proband of the family. Sanger sequencing was conducted on family members to determine if the novel variant in the KCNQ4 gene was present. Evolutionary conservation analysis and computational tertiary structure protein prediction of the wild-type KCNQ4 protein and its variant were then performed. In addition, voltage-gated channel activity of the wild-type KCNQ4 protein and its variant were tested using whole-cell patch clamp.

Results: It was observed that the proband had inherited autosomal dominant, non-syndromic sensorineural hearing loss as a trait. A novel co-segregating heterozygous missense variant (c.902C>A, p.Ala301Asp) of the KCNQ4 gene was identified in the proband and other five affected family members. This variant was predicted to cause an alanine-to-aspartic acid substitution at position 301 in the KCNQ4 protein. The alanine at position 301 is well conserved across different species. Whole-cell patch clamp showed that there was a significant difference between the WT protein currents and the mutant protein currents in the voltage-gated channel activity.

Conclusion: In the present study, performing WES in conjunction with Sanger sequencing enhanced the detection of a novel, potentially causative variant (c301 A>G; p.Ala301Asp) in exon 6 of the KCNQ4 gene. Therefore, our findings contributed to the mutation spectrum of the KCNQ4 gene and may be useful in the diagnosis and gene therapy of deafness autosomal dominant 2A.

Background: Patients with 22q11.2 microduplication syndrome exhibit a high degree of phenotypic heterogeneity and incomplete penetrance, making prenatal diagnosis challenging due to phenotypic variability. This report aims to raise awareness among prenatal diagnostic practitioners regarding the variant's complexity, providing a basis for prenatal genetic counseling.

Methods: Family and clinical data of 31 fetuses with 22q11.2 microduplications confirmed by chromosomal microarray between June 2017 and June 2023 were considered.

Results: Primary prenatal ultrasound features of affected fetuses include variable cardiac and cardiovascular anomalies, increased nuchal translucency (≥3 mm), renal abnormalities, and polyhydramnios. More than half of fetuses considered showed no intrauterine manifestations; therefore, prenatal diagnostic indicators were primarily advanced maternal age or high-risk Down syndrome screening. Most fetuses had microduplications in proximal or central 22q11.2 regions, with only three cases with distal microduplications. Among parents of fetuses considered, 87% (27/31) continued the pregnancy. During follow-up, 19 cases remained clinically asymptomatic.

Conclusion: Nonspecific 22q11.2 microduplication features in fetuses and its mild postnatal disease presentation highlight the need to cautiously approach prenatal diagnosis and pregnancy decision-making. Increased clinical efforts should be made regarding providing parents with specialized genetic counseling, long-term follow-up, and fetal risk information.

Background: We clinically and genetically evaluated a Taiwanese boy presenting with developmental delay, organomegaly, hypogammaglobulinemia and hypopigmentation without osteopetrosis. Whole-exome sequencing revealed a de novo gain-of-function variant, p.Tyr715Cys, in the C-terminal domain of ClC-7 encoded by CLCN7.

Methods: Nicoli et al. (2019) assessed the functional impact of p.Tyr715Cys by heterologous expression in Xenopus oocytes and evaluating resulting currents.

Results: The variant led to increased outward currents, indicating it underlies the patient's phenotype of lysosomal hyperacidity, storage defects and vacuolization. This demonstrates the crucial physiological role of ClC-7 antiporter activity in maintaining appropriate lysosomal pH.

Conclusion: Elucidating mechanisms by which CLCN7 variants lead to lysosomal dysfunction will advance understanding of genotype-phenotype correlations. Identifying modifier genes and compensatory pathways may reveal therapeutic targets. Ongoing functional characterization of variants along with longitudinal clinical evaluations will continue advancing knowledge of ClC-7's critical roles and disease mechanisms resulting from its dysfunction. Expanded cohort studies are warranted to delineate the full spectrum of associated phenotypes.

Background: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive disorder that predisposes individuals to hemolysis due to an inborn error of metabolism. We performed a systematic literature review to evaluate G6PD deficiency as a possible etiology of nonimmune hydrops fetalis (NIHF) and severe fetal anemia.

Methods: PubMed, OVID Medline, Scopus, and clinicaltrials.gov were queried from inception until 31 April 2023 for all published cases of NIHF and severe fetal anemia caused by G6PD deficiency. Keywords included "fetal edema," "hydrops fetalis," "glucose 6 phosphate dehydrogenase deficiency," and "fetal anemia." Cases with workup presuming G6PD deficiency as an etiology for NIHF and severe fetal anemia were included. PRISMA guidelines were followed.

Results: Five cases of G6PD-related NIHF and one case of severe fetal anemia were identified. Four fetuses (4/6, 66.7%) were male and two fetuses (2/6, 33.3%) were female. Mean gestational age at diagnosis of NIHF/anemia and delivery was 32.2 ± 4.9 and 35.7 ± 2.4 weeks, respectively. Four cases (66.7%) required a cordocentesis for fetal transfusion, and two cases (33.3%) received blood transfusions immediately following delivery. Among the four multigravida cases, two (50%) noted previous pregnancies complicated by neonatal anemia. When reported, the maternal cases included two G6PD deficiency carrier patients and two G6PD-deficient patients. Exposures to substances known to cause G6PD deficiency-related hemolysis occurred in 3/6 (50%) cases.

Conclusion: Six cases of NIHF/severe fetal anemia were associated with G6PD deficiency. While G6PD deficiency is an X-linked recessive condition, female fetuses can be affected. Fetal G6PD deficiency testing can be considered if parental history indicates, particularly if the standard workup for NIHF is negative.

Background: Marfan syndrome (MFS) is a hereditary connective tissue disorder involving multiple systems, including ophthalmologic abnormalities. Most cases are due to heterozygous mutations in the fibrillin-1 gene (FBN1). Other associated genes include LTBP2, MYH11, MYLK, and SLC2A10. There is significant clinical overlap between MFS and other Marfan-like disorders.

Purpose: To expand the mutation spectrum of FBN1 gene and validate the pathogenicity of Marfan-related genes in patients with MFS and ocular manifestations.

Methods: We recruited 318 participants (195 cases, 123 controls), including 59 sporadic cases and 88 families. All patients had comprehensive ophthalmic examinations showing ocular features of MFS and met Ghent criteria. Additionally, 754 cases with other eye diseases were recruited. Panel-based next-generation sequencing (NGS) screened mutations in 792 genes related to inherited eye diseases.

Results: We detected 181 mutations with an 84.7% detection rate in sporadic cases and 87.5% in familial cases. The overall detection rate was 86.4%, with FBN1 accounting for 74.8%. In cases without FBN1 mutations, 23 mutations from seven Marfan-related genes were identified, including four pathogenic or likely pathogenic mutations in LTBP2. The 181 mutations included 165 missenses, 10 splicings, three frameshifts, and three nonsenses. FBN1 accounted for 53.0% of mutations. The most prevalent pathogenic mutation was FBN1 c.4096G>A. Additionally, 94 novel mutations were detected, with 13 de novo mutations in 14 families.

Conclusion: We expanded the mutation spectrum of the FBN1 gene and provided evidence for the pathogenicity of other Marfan-related genes. Variants in LTBP2 may contribute to the ocular manifestations in MFS, underscoring its role in phenotypic diversity.

Background: This study aimed to identify disease-causing variants within a Chinese family affected by Birt-Hogg-Dubé syndrome (BHDS), which arises from an autosomal dominant inheritance pattern attributed to variants in the folliculin (FLCN) gene, recognized as a tumor suppressor gene.

Methods: A Chinese proband diagnosed with BHDS due to renal tumors underwent next-generation sequencing (NGS), revealing a novel variant in the FLCN gene. Sanger sequencing was subsequently performed on blood samples obtained from family members to confirm the presence of this variant.

Results: A novel germline frameshift variant (NM_144997.5:c.977dup) was identified in five individuals among the screened family members, marking the first report of this variant. Additionally, a somatic frameshift variant (NM_144997.5:c.1252del) was detected in the renal tumors of the proband. No variant was detected in unaffected family members.

Conclusions: A novel heterozygous variant was identified in exon 9 of the FLCN gene, which broadens the spectrum of FLCN variants. We recommend that molecular analysis of the FLCN gene be performed in patients with suspected BHDS and their families.

Background: Glutaric aciduria type II (GA2) is a rare genetic disorder inherited in an autosomal recessive manner. Double dosage mutations in GA2 corresponding genes, ETFDH, ETFA, and ETFB, lead to defects in the catabolism of fatty acids, and amino acids lead to broad-spectrum phenotypes, including muscle weakness, developmental delay, and seizures. product of these three genes have crucial role in transferring electrons to the electron transport chain (ETC), but are not directly involve in ETC complexes.

Methods: Here, by using exome sequencing, the cause of periodic cryptic gastrointestinal complications in a 19-year-old girl was resolved after years of diagnostic odyssey. Protein modeling for the novel variant served as another line of validation for it.

Results: Exome Sequencing (ES) identified two variants in ETFDH: ETFDH:c.926T>G and ETFDH:c.1141G>C. These variants are likely contributing to the crisis in this case. To the best of our knowledge at the time of writing this manuscript, variant ETFDH:c.926T>G is reported here for the first time. Clinical manifestations of the case and pathological analysis are in consistent with molecular findings. Protein modeling provided another line of evidence proving the pathogenicity of the novel variant. ETFDH:c.926T>G is reported here for the first time in relation to the causation GA2.

Conclusion: Given the milder symptoms in this case, a review of GA2 cases caused by compound heterozygous mutations was conducted, highlighting the range of symptoms observed in these patients, from mild fatigue to more severe outcomes. The results underscore the importance of comprehensive genetic analysis in elucidating the spectrum of clinical presentations in GA2 and guiding personalized treatment strategies.