中华医学遗传学杂志最新文献

Objective: To report and analyze a case of Juvenile neuronal ceroid lipofuscinosis (NCL) due to compound heterozygous variants of PPT1 gene.

Methods: A child who was admitted to the Department of Neurology of West China Hospital of Sichuan University in April 2021 due to "intellectual decline and behavioral abnormalities for more than 5 years and movement disorder for more than 1 year" was selected as the study subject. Clinical data of the child was collected. Trio-whole exome sequencing was carried out for the child and his parents, and clinical follow-up was conducted. This study has been approved by the Medical Ethics Committee of West China Hospital of Sichuan University (Ethic No. 2024-2286).

Results: The patient, a 13-year-old male, showed progressive mental decline, behavioral abnormalities, and movement disorders from the age of 8. Electroencephalogram showed abnormal background activities, and magnetic resonance imaging showed brain atrophy. Trio-whole exome sequencing revealed that he had harbored a paternally derived heterozygous c.272(exon3)A>C variant and a maternally derived heterozygous c.176(exon2)A>G variant of the PPT1 gene. His presentation was in keeping with previously reported juvenile NCL due to variants of the PPT1 gene.

Conclusion: The c.272(exon3)A>C and c.176(exon2)A>G compound heterozygous variants of the PPT1 gene probably underlay the Juvenile NCL in this child. Discovery of the c.176(exon2)A>G variant has expanded the mutational spectrum of this disease.

Malignant tumors are closely related to various genetic and environmental factors. Pathogenic germline gene mutations play a key role in the occurrence and development of some malignant tumors. Some germline mutations can increase the risk of malignant tumors. For example, those with homologous recombination repair gene BRCA1/2 mutations are prone to breast cancer, ovarian cancer, etc., and some germline mutations are associated with genetic syndromes. For instance, 80% of hereditary non-polyposis colon cancers are associated with mutations in mismatch repair genes such as MLH1 and MLH2. In addition, 70% of Li-Fraumeni syndrome patients have harbored germline TP53 mutations. With the development of next-generation sequencing technology, more and more germline gene mutations have been discovered recently, which is of great significance for the prevention, screening, and treatment of tumors. This article has provided a review for common germline mutations, detection methods, and advances in drug therapy.

Objective: To retrospectively analyze the results of second-trimester serological prenatal screening and explore the factors which may influence the false-positive rate (FPR).

Methods: From January 2013 to December 2022, false-positive samples with follow-up outcomes from 632,825 second-trimester serological prenatal screening samples tested at Sichuan Provincial Maternity and Child Health Care Hospital were selected as the study group, while true-negative samples were 1 : 1 matched as the control group by propensity-score matching (PSM). Univariate and binary logistic regression models were used to analyze the influencing factors. This study was approved by the Medical Ethic Committee of Sichuan Provincial Maternity and Child Health Care Hospital (Ethic No. 20240607-270).

Results: The study and control groups were each matched with 305,998 cases. Univariate analysis showed that sampling season, the difference between ultrasound and gestational weeks calculated by last menstrual period (LMP), monthly median multiple of the median (mMoM) of alpha-fetoprotein (AFP), and monthly mMoM of free β -human chorionic gonadotropin (free β -hCG) were significantly different between the two groups (P < 0.05). Binary logistic regression analysis showed that Winter (OR = 0.938; 95%CI: 0.893 ~ 0.985), monthly AFP mMoM ≥ 1.11 (OR = 0.846; 95%CI: 0.761 ~ 0.941), monthly free β -hCG mMoM ≥ 0.89 (OR = 0.827; 95%CI: 0.737 ~ 0.929) are protective factors for FPR increase, whilst Spring (OR = 1.124; 95%CI: 1.072 ~ 1.179), Summer (OR = 1.121; 95%CI: 1.062 ~ 1.183), the difference between ultrasound and gestational weeks calculated by LMP of 8 ~ 14 days (OR = 1.319; 95%CI: 1.241 ~ 1.402), < 14 days (OR = 1.689; 95%CI: 1.542 ~ 1.850), monthly AFP mMoM of 0.90 ~ 0.94 (OR = 1.088; 95%CI: 1.046 ~ 1.131), and monthly free β -hCG mMoM of 1.05 ~ 1.10 (OR = 1.046; 95%CI: 1.000 ~ 1.094), ≥ 1.11 (OR = 1.062; 95%CI: 1.002 ~ 1.126) are risk factors for FPR increase.

Conclusion: Sampling season, difference between ultrasound and gestational weeks by LMP, monthly AFP mMoM, and monthly free β -hCG mMoM are risk factors for FPR during serological prenatal screening. Screening laboratories should look for the cause of abnormal FPR through such factors and adjust them accordingly.

Objective: To analyze the association between pulmonary surfactant protein C (SP-C) gene polymorphisms and the risk of Neonatal respiratory distress syndrome (NRDS).

Methods: Clinical data from 168 neonates diagnosed with NRDS (NRDS group) admitted between August 2020 and June 2023 were collected. Additionally, 168 neonates without respiratory distress, born during the same period, were included as the control group. Peripheral venous blood samples (2 mL each) were collected from both groups. PCR-restriction fragment length polymorphism technique was employed to detect the polymorphisms at the SP-C gene loci p.Thr138Asn (rs4715) and p.Ser186Asn (rs1124). Hardy-Weinberg equilibrium tests were conducted for genotyping, and genotypic and allelic frequencies were compared. The association between SP-C gene polymorphisms and NRDS risk was evaluated. Furthermore, genotypic and allelic frequencies at the rs4715 and rs1124 loci were compared among NRDS cases with varying degrees of disease severity. The study was approved by the Medical Ethics Committee of Shangqiu First People's Hospital (Ethics No. 2020-031).

Results: The frequency of the variant allele (A) at the rs4715 locus was significantly higher in the NRDS group compared to the control group (32.14% vs. 24.11%, P = 0.001). The frequency of the variant genotype (AA + AC) was also higher in the NRDS group (47.02% vs. 39.29%, P = 0.043). The frequency of the variant allele (A) at the rs1124 locus was higher in the NRDS group compared to the control group (34.23% vs. 23.51%, P = 0.027), with a higher frequency of the variant genotype (AA + AG) in the NRDS group (49.40% vs. 39.29%, P = 0.019). No significant correlation was observed between the rs4715 polymorphism and the severity of NRDS (P > 0.05). Among NRDS children with grade III severity, the frequency of the variant allele (A) at the rs1124 locus was higher than in grade I and grade II children (47.62% vs. 29.22%, P = 0.020). The frequency of the variant genotype (AA + AG) was also higher in grade III children (64.28% vs. 43.84%, P = 0.040).

Conclusion: SP-C gene polymorphisms are associated with the susceptibility to NRDS. Neonates carrying the AA genotype and the A allele at the rs1124 locus are at a higher risk of severe NRDS. These findings have provided further evidence for early screening, diagnosis, and treatment of NRDS.

As the most common chromosomal disorder compatible to life, Down syndrome (DS) is caused by an extra copy of chromosome 21. Almost all DS patients have cognitive dysfunction. Therefore, it is important to study the underlying pathogenetic mechanism to elucidate its molecular basis. This article has provided a review for the molecular mechanisms of NRIP1 and DYRK1A genes, which have been closely associated with the cognitive dysfunctions of DS patients. It has also summarized the research progress on the mechanism of DS and development of new therapeutic strategies based on such studies, with an aim to provide insights into the prevention and treatment for the cognitive dysfunctions in DS patients.

Objective: To assess the diagnostic efficiency of long-read sequencing (LRS) for the determination of CYP21A1P/CYP21A2 and TNXA/TNXB fusion genotypes among children with 21-hydroxylase deficiency (21-OHD) and explore their clinical characteristics.

Methods: LRS sequencing was carried out on 30 children diagnosed with 21-OHD at the Department of Endocrinology, Fujian Children's Hospital between November 2022 and September 2023 by clinical symptoms or conventional Sanger sequencing combined with multiple ligation-dependent probe amplification (MLPA). The results of the two methods were compared. Clinical data of the children were collected and analyzed. This study has been approved by the Medical Ethics Committee of the Fujian Children's Hospital (Ethic No. 2022ETKLR10024).

Results: Of the 30 children with 21-OHD, 11 (36.7%) were found to carry CYP21A1P/CYP21A2 and TNXA/TNXB fusion genes by LRS. The most common type of fused CYP21A1P/CYP21A2 gene was CH-1 (72.7%), and 1 (3.3%) was found to harbor TNXA/TNXB CH-1. Eleven cases (36.7%) were found to carry large deletions by Sanger sequencing combined with MLPA, with the most common one being CYP21A2 exons 1-3 del (72.7%), which was followed by CYP21A2 exons 1-7 del (18.2%). Follow up of 11 patients carrying a fusion gene revealed that 6 were sale wasting (SW) types, 5 were simple virilizing (SV) types, whilst no non-classical (NC) type was found. Four girls had presented with central precocious puberty (CPP). One child carrying TNXA/TNXB CH-1 had presented with CAH-X syndrome.

Conclusion: Compared with Sanger sequencing combined with MLPA detection method, LRS sequencing was able to differentiate the subtypes of CYP21A1P/CYP21A2 and TNXA/TNXB fusion genes, pinpoint the breakpoints of the deletions, and directly determine the cis-trans position without the need to analyze the genotype of the pedigree members, which has provided a reliable method for the typing of 21-OHD. As some fusion genes may retain 21-hydroxylase activity, female carriers may have a higher incidence of CPP.

Objective: To explore the genetic basis for a patient with repeated fertilization failure during assisted reproductive therapy, and to identify the source and mode of mutation.

Methods: A couple treated at the Center for Reproductive Medicine, Gansu Provincial Maternal and Child Health Care Hospital in January 2024 for infertility with incomplete left tube obstruction was selected as the study subject. Relevant clinical data was collected. The couple was subjected to whole exome sequencing (WES), and the candidate variant was verified by Sanger sequencing of their family members and bioinformatic analysis.

Results: WES has identified a homozygous c.495del frameshifting mutation of the WEE2 gene in the female partner, whilst no relevant variant was suspected in the male partner. The elder brother of the female partner was homozygous for the above variant, while her parents, maternal and paternal aunts, uncle, grandmother, and grandmother were heterozygous for it. Based on the guidelines from the American College of Medical Genetics and Genomics, above variant was rated to be pathogenic.

Conclusion: The homozygous c.495del frameshifting mutation of the WEE2 gene probably underlay the oocyte fertilization disorder in this couple, which has conformed to an autosomal recessive inheritance.

Objective: To explore the clinical features and genetic variants in two children with Mowat-Wilson syndrome (MWS).

Methods: Two children admitted to the Affiliated Women and Children's Hospital of Ningbo University respectively in May and October 2022 were selected as the study subjects. Clinical data of the patients were collected. The two children were subjected to whole exome sequencing. Candidate variants were verified by Sanger sequencing and bioinformatic analysis. This study has been approved by the Medical Ethics Committee of the Women and Children's Hospital of Ningbo University (Ethic No.EC2020-014).

Results: Child 1 was a 3-year-old male who had presented with epilepsy. Cranial MRI revealed hypoplasia of corpus callosum, down-slanting eyes, hypotonia, developmental delay, and recurrent constipation. The child was found to harbor a de novo c.262dup (p.Ile88Asnfs*31) missense variant of the ZEB2 gene, which was detected in neither parents. Child 2 was a 6-months-old male presented with epilepsy, with no apparent anomaly detected by cranial MRI. The child had featured developmental delay, inverted eyelash, atrial septal defect, and cryptorchidism. WES revealed that he had harbored a c.3213_3224delinsCTAC (p.Q1072Yfs*49) frameshifting variant of the ZEB2 gene, which was detected in neither parents. Based on the guidelines from the American College of Medical Genetics and Genomics, both variants were determined as likely pathogenic, with ratings of PVS1_Strong+PM2_Supporting+PM6 and PVS1_Strong+PM2_Supporting+PM6. Both variants had resulted in premature occurrence of stop codons.

Conclusion: By combining their clinical features and results of genetic testing, both children had been diagnosed with MWS due to variants of the ZEB2 gene. Above findings have enriched the mutational spectrum of MWS and provided a basis for the prenatal diagnosis and genetic counseling.

Objective: To explore the genetic basis for a Chinese pedigree affected with Fragile X syndrome (FXS) through Nanopore long-read sequencing.

Methods: A FXS pedigree who had undergone genetic counseling at the First Affiliated Hospital of Zhengzhou University in April 2023 was selected as the study subject. Nanopore long-read sequencing, triplet-repeat primed PCR (TP-PCR), methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) and trinucleotide polymorphism genotyping of androgen receptor (AR) gene were used to analyze the FMR1 CGG repeat number, methylation, and X chromosome inactivation of the pedigree members. This study has been approved by the Medical Ethics Committee of the First Affiliated Hospital of Zhengzhou University (No. KS-2018-KY-36).

Results: Full mutation and CpG island hypermethylation were detected in the proband. The elder sister of the proband had full mutation of the FMR1 gene on one X chromosome and hypermethylation of CpG island, while the FMR1 gene on the other X chromosome was normal. FMR1 premutation was detected in the proband's mother.

Conclusion: Nanopore long-read sequencing can simultaneously detect the dynamic mutation and methylation status of the FMR1 gene on the two X chromosomes of females, which has important value for the diagnosis of FXS in different genders.

V-ATPases are a class of multi-subunit protein complexes that utilize energy derived from ATP hydrolysis for mediating H⁺ transport across cell membranes, which plays an important role in a range of life activities by acidifying the intracellular and extracellular environment. Variants of V-ATPase genes may lead to complete or partial loss of V-ATPase activity, which in turn may impair the ability of type A intercalated cells in renal tubules to pump H⁺ into the tubular lumen, ultimately resulting in the onset of autosomal recessive distal renal tubular acidosis (dRTA). With the rapid development of molecular techniques, ATP6V0A4 and ATP6V1B1 have now been identified as the pathogenic genes for dRTA. Moreover, animal and cell experiments have substantiated the implication of V-ATPase subunit genes including ATP6V1C2 and ATP6V1G3 in the development of dRTA, though clinical evidence is still limited. This article has reviewed recent progress on the genetic and molecular mechanisms of V-ATPase subunit gene variants which can lead to dRTA, which may shed light on the diagnosis and treatment of this disease.