中华医学遗传学杂志最新文献

Objective: To explore the clinical characteristics and genetic variants underlying Hereditary coagulation factor V (FV) deficiency in two Chinese pedigrees.

Methods: Seventeen individuals from three generations of the two pedigrees affected with FV deficiency whom had visited Taizhou Hospital of Zhejiang Province respectively in March and June 2024 were recruited as study subjects. One hundred healthy individuals undergoing physical examinations have served as the controls. Relevant coagulation parameters were measured. Thrombin generation was assessed using the calibrated automated thrombogram (CAT) assay. All exons and flanking regions of the F5 gene were amplified by PCR and directly sequenced. Candidate variants were analyzed for evolutionary conservation and potential pathogenicity, and their effects on protein structure were predicted. This study was approved by the Medical Ethics Committee of Taizhou Hospital of Zhejiang Province (Ethics No.: 20230722).

Results: The FV activity (FV: C) and antigen levels (FV: Ag) of both probands showed concurrent decrease. By thrombin generation assay, both the lag time ratio and time to peak ratio were significantly increased. Genetic analysis revealed that proband A carried compound heterozygous missense variants c.911G>A (p.Gly304Glu) and c.1238T>C (p.Met413Thr), whilst Proband B carried compound heterozygous missense variants c.1258G>T (p.Gly420Cys) and c.1538G>A (p.Arg513Lys) of the F5 gene. Conservation analysis revealed that the amino acid residues p.Gly304, p.Gly420, and p.Arg513 are highly conserved across various species. Online bioinformatics tools predicted that both the p.Gly304Glu and p.Gly420Cys variants are pathogenic. Protein modeling demonstrated that all four variants can result in alterations of protein structure or disruption of hydrogen bonding.

Conclusion: FV deficiency in these two pedigrees can be attributed to the compound heterozygous variants p.Gly304Glu/p.Met413Thr and p.Gly420Cys/p.Arg513Lys of the F5 gene.

Objective: To explore the clinical manifestations and genetic etiology of a child with Progressive familial intrahepatic cholestasis (PFIC2).

Methods: From April 2024 to June 2024, a child with jaundice, hepatomegaly and abnormal liver function who was repeatedly admitted to the First Department of Pediatrics of Qinzhou Maternal and Child Health Care Hospital was selected as the study subject. Clinical data of the child were collected. Peripheral blood samples were collected from the child and her parents. Genomic DNA was extracted for trio-whole exome sequencing, the candidate variant was verified by Sanger sequencing and bioinformatic analysis using REVEL, BLAST/BLAT, Swiss-Model and Swiss-Pdb Viewer software. This study was approved by the Medical Ethics Committee of the Qinzhou Maternal and Child Health Care Hospital (Ethics No.: L20240116).

Results: The child was a 1.5-month-old female. Her main clinical manifestations included jaundice, hepatomegaly, brownish urine and earth-like stool. Laboratory examination showed increased levels of bilirubin, mainly direct bilirubin, increased aminotransferase, especially glutamic oxalacetic aminotransferase, accompanied by increased bile acid. Genetic testing revealed that the she has harbored a homozygous c.3410T>G (p.V1137G) variant of the ABCB11 gene, for which both of her parents were heterozygous carriers. The variant was unreported previously, and was predicted to be pathogenic based on REVEL. Prediction with BLAST/BLAT software showed that the amino acids were highly conserved among different species. Swiss-Pdb Viewer software predicted that the variant has resulted in changes in hydrogen bonds between amino acids. According to the guidelines from the American Collage for Medical Genetics and Genomics (ACMG), the variant was determined to be likely pathogenic (PM1+PM2_Supporting+PM3_Supporting+PP3_Moderate).

Conclusion: The homozygous variant of the ABCB11 gene may be the genetic cause of this child. Genetic testing is helpful for confirming the diagnosis and enrich the mutational spectrum of the ABCB11 gene.

Objective: To investigate the clinical phenotype and genetic etiology of a patient with tall stature and primary amenorrhea presenting with 47,XYY Disorder of sex development (DSD).

Methods: A female patient presenting with "tall stature and primary amenorrhea" at Nanjing Drum Tower Hospital in July 2024 was selected as the study subject. A retrospective study design was employed to collect the patient's clinical data. Peripheral venous blood sample was collected. Following the extraction of genomic DNA, genetic testing was performed including chromosomal karyotyping analysis, copy number variation sequencing (CNV-seq), multiplex PCR for the AZF regions and sex-determining genes Y (SRY), and whole-exome sequencing (WES). Candidate variants were validated by Sanger sequencing and classified for pathogenicity based on the guidelines from the American College of Medical Genetics and Genomics (ACMG). This study was approved by the Medical Ethics Committee of Nanjing Drum Tower Hospital (Ethics No.: 2022-451-01).

Results: The patient had a height of 188 cm and a body weight of 50 kg, in addition with infantile uterus, absent ovaries, and primary amenorrhea. G-banded karyotyping analysis of peripheral blood sample revealed 47,XYY. CNV-seq indicated Seq[GRCh37]Yp11.32q12×2. No deletion was detected in the AZF regions of Y chromosome, and SRY was positive. WES identified a heterozygous c.86C>A (p.Thr29Lys) variant of the NR5A1 gene, leading to substitution of threonine with lysine at position 29 of the encoded protein. Sanger sequencing confirmed the presence of the variant. According to the ACMG guidelines, this variant was classified as variant of uncertain significance (VUS) with supporting evidence (PS3_Moderate+PM5+PP3+PM2_Supporting+PS4_Supporting). Reviewing the nearly 60 years of previously reported cases, all 7 documented 47,XYY DSD patients were assigned a female social gender and presented with abnormal gonadal and external genitalia development. Among them, 5 cases underwent SRY testing, all of which were positive. Only 1 case underwent whole-exome sequencing (WES), but no pathogenic or likely pathogenic variants were identified.

Conclusion: This DSD patient presented with the clinical features of tall stature and primary amenorrhea. The NR5A1 gene variant c.86C>A (p.Thr29Lys) probably underlay the Disorder of sex development in this patient. Above finding has enriched the spectrum of pathogenic variants of the NR5A1 gene.

Objective: To explore the genetic etiology of Pontocerebellar Hypoplasia Type 2D (PCH2D) due to compound heterozygous variants of the SEPSECS gene and to conduct a literature review.

Methods: A child with PCH2D diagnosed at the Children's Hospital of Nanjing Medical University due to "motor and cognitive retardation" in June 2022 was selected as the study subject. Clinical and imaging data were collected. Genomic DNA was extracted from the peripheral blood samples of the child and her parents. Whole-exome sequencing (WES) was conducted using capture-based high-throughput sequencing technology. Candidate variants were confirmed by Sanger sequencing and bioinformatics analysis. The pathogenicity of variant was rated according to the Standards and Guidelines for the Interpretation of Sequence Variants released by American College of Medical Genetics and Genomics (ACMG). Additionally, relevant literature on PCH2D caused by SEPSECS gene variants was reviewed to assess the genotype-phenotype correlation. This study was approved by the Medical Ethics Committee of the hospital (Ethical No.: 202402022-1).

Results: The child, a 1-year-and-3-month-old girl, had presented with global developmental delay, progressive microcephaly, hypotonia, elevated blood lactic acid, feeding difficulties, and absent tendon reflexes. Cranial MRI indicated thinning of the splenium of the corpus callosum. Electromyography suggested peripheral neurogenic changes primarily affecting sensory nerves. WES revealed the she has harbored compound heterozygous variants of the SEPSECS gene, namely c.194A>G (p.N65S) and c.896_c.897insA (p.N299fs*2) (NM_016955), which were inherited from her father and mother, respectively. Neither of her parents had related clinical manifestations. According to the ACMG guidelines, the c.194A>G (p.N65S) variant was classified as pathogenic (PM1+PM2_Supporting+PM3+PP3), and the c.896_c.897insA (p.N299fs*2) variant was as likely pathogenic (PVS1+PM2_Supporting). A total of 18 relevant literature were retrieved, which have involved 32 patients (including this case). The p.N65S variant has been reported previously, while the p.N299fs*2 variant is novel.

Conclusion: Compound heterozygous variants in the SEPSECS gene probably underlay the pathogenesis of PCH2D in this child. Above finding has expanded the mutational and phenotypic spectrum of the SEPSECS gene.

Objective: To investigate the clinical manifestations and genetic characteristics of a child with glycogen storage disease type III (GSD-III) complicated with Guillain-Barré syndrome (GBS) caused by AGL gene variants, and to analyze the pathogenesis, potential correlation, treatment and prognosis of the two diseases.

Methods: A child with GSD-III who visited the General Hospital of Ningxia Medical University due to "limb weakness for more than ten days" in July 2024 was selected as the study subject. Clinical data of the child were collected. Peripheral blood samples of the child and his parents were collected for whole exome sequencing and Sanger sequencing. Candidate variants were verified, and pathogenicity analysis was conducted for the variant sites. This study was approved by the Medical Ethics Committee of General Hospital of Ningxia Medical University (Ethics No.: KYLL-2025-1984).

Results: The child has presented with inability to stand or walk independently, difficulty in grasping, accompanied by numbness and pain at the distal end, choking when drinking water, occasional non-projectile vomiting, and enlargement of liver and spleen. Laboratory tests showed abnormal liver function and a significant increase in creatine kinase. Color Doppler ultrasound of the heart showed an enlarged left atrium and mild regurgitation of mitral and tricuspid valves. Genetic testing confirmed that he has harbored compound heterozygous variants of the AGL gene, namely c.1611G>A (p.E537E) and c.579del (p.W194Gfs*7), which were inherited from his father and mother, respectively. According to the guidelines from the American Collage for Medical Genetics and Genomics (ACMG), the two variants were respectively predicted as variant of unknown significance (PM2_Supporting+PM3+PP3_Supporting) and likely pathogenic (PVS1+PM2_Supporting). Electrophysiological examination confirmed that the child had severe damage to the motor and sensory nerves accompanied by axonal injury, which was consistent with the axonal variant type of GBS -acute motor and sensory axonal neuropathy. After a clear diagnosis, the child was treated with intravenous human immunoglobulin. His condition deteriorated progressively, presenting with breathing difficulties, liver failure, and gastrointestinal bleeding, and eventually deceased due to multiple organ failures.

Conclusion: The etiology of GSD-III and GBS involves multiple aspects such as genetics, metabolism and immunity. In clinical practice, it should be noted that similar clinical manifestations may occur in both conditions. Close attention should be paid to the patients' blood glucose, blood gas, coagulation function and liver function, etc. Clinical intervention should be carried out as early as possible to improve the prognosis.

Objective: To investigate the association between SPAG17 gene variant and Familial severe asthenozoospermia, and to assess its impact on the outcome of intracytoplasmic sperm injection (ICSI).

Methods: Two siblings (Probands 1 and 2) with severe asthenozoospermia from a Chinese family who presented at the Reproductive Medicine Center II of Gansu Maternity and Child Health Care Hospital (Gansu Provincial Central Hospital) in May 2023 were selected as study subjects. Clinical data were collected, and sperm morphology and ultrastructure (assessed by transmission electron microscopy) were analyzed. Pathogenic variants were screened using whole exome sequencing (WES) and verified by Sanger sequencing. This study was approved by the Medical Ethics Committee of Gansu Maternity and Child Health Care Hospital (Ethics No.: 2023GSFYLS78).

Results: Probands 1 and 2 had primary infertility for 10 and 3 years, respectively, and both exhibited normal semen concentration, but the percentage of progressive motile sperm (PR) was significantly lower than the normal reference value (> 32.00%), measuring 2.33% ± 0.58% and 0.80% ± 0.45%, respectively. Additionally, the percentage of sperms with normal morphology was slightly below the reference range (> 4.00%), with the values of 3.36% ± 0.35% and 2.93% ± 1.36%. Both probands were found to harbor homozygous c.2188C>T (p.Q730*) nonsense variant of the SPAG17 gene (NM_206996.4), for which their mother was a heterozygous carrier (their father had already deceased). Both sibs underwent ICSI treatment using a long gonadotropin-releasing hormone agonist protocol during the follicular phase combined with assisted oocyte activation (AOA). The wife of Proband 1 ultimately gave birth to a healthy girl, whilst the wife of Proband 2 delivered two healthy girls.

Conclusion: The homozygous c.2188C>T (p.Q730*) nonsense variant of the SPAG17 gene is closely related with the severe asthenozoospermia phenotype. Live births can be achieved through ICSI combined with AOA technology, though the overall utilizable embryo rate may be relatively low.

Objective: To investigate the steady-state mechanism of interconversion between the SMN1 and SMN2 genes in a normal population.

Methods: Fluorescence PCR capillary electrophoresis was employed to assess gene conversion and copy number variation of SMN1 and SMN2 in a cohort of 1,133 healthy individuals (including 256 males and 877 females) recruited between 2019 and 2023. This study was approved by the Ethics Committee of Henan Provincial People's Hospital (Ethics No.: 2019-134).

Results: No significant gender difference was observed in the single copy carrying rate of SMN1. The probability of conversion from SMN1 to SMN2 was determined to be 3.2% for females, 2.7% for males, and 3.1% for the overall population. The probability of conversion from SMN2 to SMN1 was found to be 5.5% for females, 6.3% for males, and 5.6% for the overall population. No statistically significant difference was found in the conversion probability between different genders (P > 0.05). Among the 99 cases of gene conversion, the SMN1 gene predominantly exhibited a copy number of 2 (97.0%), with the remainder having 3 copies (3%). The SMN2 gene primarily showed a copy number of 2 (72.7%), with the rest having 1 copy (27.3%).

Conclusion: Gene conversion tends to normalize the copy numbers of both SMN1 and SMN2 genes towards 2. However, SMN1 exhibited a higher priority over SMN2, causing the copy numbers approaching two.

Objective: To report on a case of mosaicism involving trisomy 21, maternal uniparental isodisomy, and normal diploid cells in uncultured amniocytes, and to explore the discrepancies between conventional cytogenetic and molecular cytogenetic techniques during prenatal diagnosis.

Methods: A 30-year-old pregnant woman who presented to Boai Hospital of Zhongshan on June 27, 2023 has undergone amniocentesis at 16 weeks of gestation. The amniotic fluid sample was subjected to quantitative fluorescent PCR (QF-PCR), G-banded karyotype analysis, and chromosomal microarray analysis (CMA). The discrepancies between the results of each method were analyzed. This study was approved by Medical Ethics Committee of Boai Hospital of Zhongshan (Ethics No.: KY-2024-001-01).

Results: Non-invasive prenatal testing (NIPT) at 12 weeks indicated a high risk of trisomy 21. QF-PCR of uncultured amniocytes revealed a pattern of trisomy 21. After one week of cell culture, G-banding analysis showed mos 47,XX,+21[1]/46,XX[72]. CMA revealed a homozygous state of chromosome 21 in cultured cells, while uncultured amniocytes showed mosaic trisomy 21 with an estimated proportion of 50%. These findings suggested a complex chromosomal mosaicism in the fetus, which may result from a trisomy rescue event during early embryogenesis, leading to coexistence of three cell lines including trisomy 21, maternal uniparental isodisomy, and normal diploid cells.

Conclusion: In prenatal diagnosis, discrepancies may arise between QF-PCR and conventional chromosomal karyotyping analysis, particularly in complex genetic phenomena such as trisomy rescue and uniparental disomy. For cases where NIPT indicated a high risk of trisomy 21 but G-banding karyotype analysis yielded a normal result, further molecular genetic testing using uncultured cells is recommended.

Objective: To investigate the clinical characteristics and genetic etiology of a fetus with bilateral ear malformation and microphthalmia.

Methods: A fetus diagnosed with Syndromic Microphthalmia 5 (MCOPS5) on January 29, 2024 at Ningbo Women and Children's Hospital was selected as the study subject. A retrospective study was conducted to collect clinical data. Peripheral blood samples (3 mL) were collected from the parents, and amniotic fluid (10 mL) was obtained from the fetus. Genomic DNA was extracted and subjected to whole-exome sequencing (WES). Candidate variants were validated by Sanger sequencing of the family members. The pathogenicity of the candidate variant was classified according to the guidelines from the American College of Medical Genetics and Genomics (ACMG). This study was approved by the Ethics Committee of Ningbo Women and Children's Hospital (Ethics No.: EC2023-094).

Results: The gestational age of the fetus was 23⁺² weeks. Prenatal magnetic resonance imaging (MRI) revealed hypoplastic left external ear, bilateral reduced eyeball volume, and abnormal brain parenchyma development. WES has identified a heterozygous frameshift variant in the OTX2 gene (NM_021728.4: c.706_725del, p.Thr236ProfsTer17). Sanger sequencing confirmed that neither parent has carried the same variant, indicating a de novo origin. According to the ACMG guidelines, this variant was classified as likely pathogenic (PVS1_Strong+PM2_Supporting+PS2_Supporting).

Conclusion: The heterozygous frameshift variant (NM_021728.4: c.706_725del) of the OTX2 gene probably underlay the pathogenesis of this fetus. Above finding has expanded the mutational spectrum of OTX2 gene and may contribute to the understanding of syndromic microphthalmia.

Objective: To explore the genetic basis for a woman with oocyte maturation disorder during assisted reproductive treatment (ART), and to verify the source of the variant and its impact on oocyte maturation through family verification.

Methods: A 35-year-old infertile woman presented at the Reproductive Medicine Center of Gansu Provincial Maternal and Child Health Care Hospital on 20 October 2023 for a 10-year history of infertility despite unprotected intercourse was selected as study subject. Peripheral venous blood sample was collected from the proband. Next-generation sequencing (NGS) was used to detect the potential variant. Candidate variants were validated within her family by Sanger sequencing, and their deleteriousness was assessed with comprehensive bioinformatic analyses to elucidate their origin and impact on oocyte maturation. According to the Standards and Guidelines for the Interpretation of Sequence Variants (hereinafter referred to as ACMG Guidelines) formulated by the American College of Medical Genetics and Genomics (ACMG), the pathogenicity of the candidate variant was rated. This study was approved by the Medical Ethics Committee of Gansu Provincial Maternal and Child Health Care Hospital (Ethics No.: 2023GSFYLS78).

Results: The proband underwent three controlled ovarian-stimulation cycles as part of assisted reproductive technology, yielding a total of 29 oocytes, among which only three were mature, whilst the remainders exhibited maturation arrest. Targeted sequencing of peripheral-blood DNA revealed a heterozygous c.728C>T (p.P243L) missense variant of the TUBB8 gene. While the same variant was detected in the proband's father. Based on the ACMG guidelines, the variant was classified to be likely pathogenic (PS4_Supporting+PM2_Supporting+PP2+PP3+PP4).

Conclusion: The heterozygous c.728C>T (p.P243L) missense variant of the TUBB8 gene probably underlay the oocyte maturation disorder in the proband, which may be either autosomal dominant or autosomal recessive. For probands with oocyte maturation disorders caused by the heterozygous c.728C>T variant of the TUBB8 gene, oocyte donation may be considered.