OBJECTIVE: To explore the genetic basis for two Chinese pedigrees affected with Huntington disease and provide prenatal diagnosis for them. METHODS: Peripheral venous blood samples were collected from the probands. PCR and capillary gel electrophoresis were used to determine the number of CAG repeats in their IT15 gene. Pre-symptomatic testing was offered to their children and relatives, and prenatal diagnosis was provided to three pregnant women from the two pedigrees. RESULTS: The two probands, in addition with three asymptomatic members, were found to have a (CAG)n repeat number greater than 40. Upon prenatal diagnosis, the numbers of CAG repeats in two fetuses from pedigree 1 were determined as (16, 19) and (18, 19), both were within the normal range. A fetus from pedigree 2 was found to have a CAG repeat number of (15, 41), which exceeded the normal range. CONCLUSION Genetic testing can facilitate the diagnosis of Huntington disease and avoid further birth of affected children.
Child ; Female ; Genetic Testing ; Humans ; Huntington Disease/genetics* ; Nerve Tissue Proteins/genetics* ; Pedigree ; Pregnancy ; Prenatal Diagnosis

Objective:To summarize initial experience of applying nanopore third-generation sequencing detection method (nanopore sequencing) for genetic diagnosis of non-classical 21 hydroxylase deficiency (NC 21-OHD), and to explore its performance and application prospects.Methods:Clinical data of the two NC 21-OHD patients, who were hospitalized at the First Affiliated Hospital of Zhengzhou University in May 2019, were collected. Peripheral venous blood was collected and genome DNA extracted. Genetic variants was detected by nanopore sequencing and underwent bioinformatic analysis. Pathogenetic mutations in CYP21A2 gene were validated with PCR-sanger sequencing in the two patients and their parents.Results:The average reads length and sequence depth in the patient one was 12, 792 bp and 27.19×. The average reads length and sequence depth in the patient two was 13, 123 bp and 21.34×. Compound variants of c.293-13C>G/c.844G>T (p.Val282Leu) and c.332_339delGAGACTAC (p.Gly111Valfs)/c.844G>T (p.Val282Leu) were detected in these two patients, which were consistent with clinical phenotype of NC 21-OHD. Further analysis showed that c.293-13C>G mutation was inherited from her father and c.844G>T (p.Val282Leu) mutation was inherited from her mother for the patient one. The c.844G>T (p.Val282Leu) mutation was inherited from her father and c.332_339delGAGACTAC (p.Gly111Valfs) mutation from her mother.Conclusions:The heterozygous mutations in CYP21A2 gene are the cause of NC 21-OHD in these two patients. Nanopore sequencing technique is a reliable new detection method for patients with NC 21-OHD.

Objective:To detect and analyze the gene variation types of 64 unrelated pedigrees affected with autosomal dominant polycystic kidney disease (ADPKD), and explore the detection efficiency of multiple gene analysis techniques and variation characteristics.Methods:It was a cross-sectional study. The clinical data of 64 pedigrees with ADPKD from Nephrology Department or Genetic and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University from December 2017 to August 2020 were retrospectively analyzed. The blood samples of probands and other family members were collected. Genetic analysis was carried out by next generation sequencing, and suspected mutations were verified by multiplex ligation-dependent probe amplification, or long-range PCR combined with Sanger sequencing. Prenatal diagnosis for high-risk fetuses was performed by fetal villi or amniotic fluid cells after genotyping without maternal genomic DNA contamination.Results:Among detected 64 pedigrees, 57 pedigrees (89.06%) had genetic variants in PKD1/PKD2. A total of 49 pathogenic/likely pathogenic variants in PKD1/PKD2 were identified in 51 pedigrees (79.69%), including 14 nonsense variants (28.57%), 14 frameshift variants (28.57%), 11 missense variants (22.45%), 5 splicing variants (10.20%) and 5 deletion variants (10.20%). Of these variants, 87.76% (43/49) were in PKD1 and 12.24% (6/49) were in PKD2. Totally, 14 novel variants in PKD1/ PKD2 were identified, including 7 frameshift variants, 3 splicing variants, 2 nonsense variants, 1 deletion variant and 1 missense variant, of which 11 variants were in PKD1 and 3 variants were in PKD2. Twenty high-risk fetuses from 17 pedigrees received prenatal diagnosis, in whom 6 fetuses had PKD1 variation, and other 14 fetuses had no PKD1/ PKD2-genetic variation. Conclusions:The combination of next-generation sequencing, multiplex ligation-dependent probe amplification, and long-range PCR combined with Sanger sequencing can be helpful for rapid, efficient and accurate genetic diagnosis of ADPKD pedigrees. Point mutations are the most common types in PKD1/PKD2. Fourteen novel variants in PKD1/PKD2 extend its pathogenic variant spectrum and can provide basis for genetic counseling and prenatal diagnosis of ADPKD pedigrees.

Objective:To explore the genetic etiology of a Chinese pedigree affected with Branchio-oculo-facial syndrome (BOFS) and summarize the prenatal phenotype of BOFS patients.Methods:A pedigree with BOFS which had presented at the Genetics and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University in December 2021 was selected as the study subject. Clinical data of the pedigree was collected. The fetus was subjected to routine prenatal ultrasound scan. Trio-whole exome sequencing (trio-WES) was carried out for the fetus and its parents, and candidate variant was verified by Sanger sequencing. Relevant literature was searched from the database to summarize the prenatal phenotype of BOFS patients. This study was approved by the First Affiliated Hospital of Zhengzhou University (Ethics No. KS-2018-KY-36).Results:Ultrasound exam suggested the fetus had cleft lip and palate. Its father had presented with high palatal arch, prematurely grayed hair, occult cleft lip, congenital preauricular fistula, red-green color blindness and unilateral renal agenesis. Its grandfather also had high palatal arch, prematurely gray hair, protruding ears, congenital preauricular fistula and hearing disorders. Trio-WES revealed that the fetus and its father had both harbored a heterozygous c. 890-1G>A variant of the TFAP2A gene. The same variant was not found in its mother. Sanger sequencing confirmed that its grandfather had also harbored the same variant. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was rated as likely pathogenic (PVS1+ PM2_Supporting). Combined with 36 similar cases retrieved from the literature, the prenatal phenotypes of BOFS patients had included growth restriction (25/37), renal abnormalities (10/37), cleft lip and palate (5/37) and oligohydramnios (5/37). Conclusion:The c. 890-1G>A variant of the TFAP2A gene probably underlay the pathogenesis of BOFS in this pedigree. Discovery of the novel variant has enriched the mutational spectrum of the TFAP2A gene. The common prenatal phenotypes of BOFS have included growth restriction, renal abnormalities, cleft lip and palate and oligohydramnios. Delineation of the intrauterine phenotype of BOFS may facilitate its prenatal diagnosis, clinical diagnosis, treatment and genetic counseling.