Objective:To analyze the clinical and genetic characteristics of ten Chinese pedigrees affected with 7q11.23 duplication syndrome.Methods:From December 2017 to January 2022, ten pedigrees diagnosed with 7q11.23 duplication syndrome at the First Affiliated Hospital of Zhengzhou University were enrolled as the study subjects. Clinical data of all subjects were collected, and some had subjected to copy number variation sequencing or single nucleotide polymorphism array to analyze the pattern of inheritance.Results:The probands had included six fetuses and four adolescents. Four of the six prenatal cases showed abnormal ultrasound indicators, including three with soft indicators and one with abnomal feta structural development. The clinical phenotype of the four adolescent cases had included mental retardation, delayed language development, and attention deficit hyperactivity disorder. The size of the copy number variations had ranged from 1.31 to 1.42 Mb, involving the classic region of 7q11.23 duplication syndrome. Of these, five cases had undergone parental origin testing, three cases were de novo, and two were hereditary. Conclusion:Individuals with 7q11.23 duplication syndrome may show substantial clinical phenotypic heterogeneity, hence the affected families should be provided with pre-pregnancy consultation and reproductive guidance.

Objective:To explore the genetic etiology of a child with delayed growth and development and carry out a literature review.Methods:A child suspected for Al Kaissi syndrome at the First Affiliated Hospital of Zhengzhou University on March 6, 2021 was selected as the study subject. Following extraction of genomic DNA, the child was subjected to copy number variation sequencing (CNV-seq) and whole exome sequencing (WES), and candidate variants were verified by PCR-agarose gel electrophoresis and quantitative real-time PCR (qPCR). Prenatal diagnosis was conducted on chorionic villi sample upon subsequent pregnancy.Results:The child, a 6-year-and-4-month-old boy, has dysmorphic features including low-set protruding ears and triangular face, delayed language and intellectual development, and ventricular septal defect. CNV-seq result has found no obvious abnormality, whilst WES revealed homozygous deletion of exons 1 and 2 of the CDK10 gene, which was confirmed by PCR -agarose gel electrophoresis and qPCR. Both of his parents were heterozygous carriers. Prenatal diagnosis using chorionic villi samples suggested that the fetus also carried the heterozygous deletion.Conclusion:The clinical features of Al Kaissi syndrome in this child can probably be attributed to the homozygous deletion of exons 1 and 2 of the CDK10 gene.

Objective:To explore the clinical and genetic characteristics of a neonate with Microvillus inclusion disease (MVID).Methods:A neonate with MVID admitted to the First Affiliated Hospital of Zhengzhou University in May 2019 was selected as the study subject. Clinical data were collected. Whole exome sequencing (WES) was carried out, and candidate variants were verified by Sanger sequencing and multiple ligation-dependent probe amplification (MLPA). A literature was also carried out to summarize the clinical and genetic characteristics of MVID.Results:The prematurely born neonate had presented with unexplained refractory diarrhea and metabolic acidosis. Active symptomatic treatment was ineffective, and the child had died at 2 months old. WES revealed that he had harbored compound heterozygous variants of the MYO5B gene, namely c. 1591C>T (p.R531W) and deletion of exon 9. Sanger sequencing showed that the R531W variant was inherited form his father, and MLPA confirmed that the exon 9 deletion was inherited from his mother. Seven children with MVID were reported in China, of which one was lost during follow-up and six had deceased. One hundred eighty eight patients were reported worldwide and only one was cured. The clinical features of MVID had included refractory diarrhea, metabolic acidosis and poor prognosis. Conclusion:The child was diagnosed with MVID due to the compound heterozygous variants of the MYO5B gene, which has provided a basis for genetic counseling and prenatal diagnosis.

Fetal structural anomalies and birth defects are primarily caused by genetic variants such as chromosomal number abnormalities, copy number variations (CNV), single nucleotide variants (SNV), and small insertions and deletions (indel). Whole-genome sequencing (WGS) based on next-generation sequencing (NGS) as an emerging technology for genetic disease diagnosis can detect the aforementioned types of variants. In recent years, high-depth WGS (> 30×) for prenatal diagnosis has also become available, and proved to be practical for unraveling the genetic etiology of fetal developmental abnormalities. To fascilitate clinical practice, test development and preliminary implementation of WGS for diagnosing fetal structural anomalies, we have formulated a consensus over the application of WGS in prenatal diagnosis by compiling previously published consensuses, guidelines, and research findings to provide a guidance on data analysis, reporting recommendations, and consultation of prenatal WGS results.

Uniparental disomy (UPD)-related imprinting disorders are a group of congenital disorders which can lead to severe birth defects. Their molecular etiology is the occurrence of UPD in the genomic imprinting regions, which may cause disturbed expression of parent-of-origin imprinted genes. With the widespread applications of genetic testing techniques, the prenatal diagnosis of UPD-related imprinted diseases has gradually become clinical routines. However, due to the complicated pathogenesis of such disorders, currently there is still a lack of standards and norms for the understanding, diagnosis, management and genetic counseling. By referring to the relevant guidelines and consensus, the latest progress of research, and opinions from experts in the relevant fields, the writing group has formulated a consensus over the prenatal diagnosis and genetic counseling for UPD-related imprinting disorders, with an aim to provide a more accurate and rational evaluation in prenatal clinics.

Objective:To explore the characteristics of phenylalanine hydroxylase ( PAH) gene variants and prenatal diagnosis for 43 Chinese pedigrees affected with Phenylketonuria (PKU). Methods:Forty three PKU pedigrees diagnosed at the First Affiliated Hospital of Zhengzhou University between 2019 and 2021 were selected as the study subjects. Variants of the PAH gene of the probands were screened by high-throughput sequencing, and candidate variants were verified by Sanger sequencing. Negative cases were further analyzed by multiplex ligation-dependent probe amplification (MLPA) to detect large fragment deletions and duplications of the PAH gene. For 43 women undergoing subsequent pregnancy, Sanger sequencing, MLPA, combined with short tandem repeats (STR) sequence-based linkage analysis, were carried out for prenatal diagnosis. Results:Among the 86 alleles carried by the 43 probands, 78 nucleotide variants (90.70%) and 3 large deletions (3.49%) were found based on high-throughput sequencing and MLPA. The 81 mutant alleles had included 21 missense variants, 5 splice site variants, 4 nonsense variants, 2 microdeletions, 1 insertional variant and 2 large fragment deletions. Relatively common variants have included p. Arg243Gln (23.26%), p. Arg111Ter (8.14%), EX6-96A>G (6.98%), p. Val399Val (5.81%) and p. Arg413Pro (4.65%). Most of the variants were located in exons 7, 11, 3, 6 and 12. For the 43 families undergoing prenatal diagnosis, 9 fetuses (20.45%) were diagnosed with PKU, 20 (45.45%) were heterozygous carriers, and 15 (34.09%) did not carry the same pathogenic allele as the proband. All neonates were followed up till 6 months old, and the accuracy of prenatal diagnosis was 100%.Conclusion:The combination of high-throughput sequencing, Sanger sequencing, MLPA and linkage analysis can increase the diagnostic rate of PKU and attain accurate prenatal diagnosis.

Objective:To investigate the clinical and genetic features of a child with Dyschromatosis symmetrica hereditaria (DSH) and variant of the ADAR1 gene. Methods:A child who was admitted to the Department of Dermatology of the First Affiliated Hospital of Zhengzhou University in June 2020 due to irregular pigmented maculopapular rash on the dorsum of hands was selected as the study subject. Whole exome sequencing (WES) was carried out for the child and his similarly affected father, and Sanger sequencing was used to verify the candidate variant. SWISS-MODEL was used to predict the secondary and tertiary structures of the wild-type and mutant ADAR1 proteins.Results:The child, a 13-year-old boy, had symmetrical hyperpigmented and depigmented spots on the back of his hands and was clinically diagnosed with DSH. WES and Sanger sequencing results showed that he and his father had both harbored a heterozygous c. 2858dup (p.T954Dfs*20) truncating variant in exon 10 of the ADAR1 gene. Based on the guidelines from the American College of Medical Genetics and Genomics, the variant was predicted as pathogenic (PVS1+ PM2_Supporting+ PM1+ PP3). Conclusion:The c. 2858dup (p.T954Dfs*20) variant of the ADAR1 gene probably underlay the DSH in this pedigree.

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.

Clinical application of serological screening and non-invasive prenatal testing (NIPT) both have difficulties to attain high detection rate and low cost. For its advantages of high detection rate, high sensitivity, simplicity, short turnaround time and low cost, digital PCR (dPCR) has provided a new choice for prenatal screening of trisomies 21, 18 and 13. To standardize the application of dPCR for prenatal screening, we have formulated this consensus by referring to relevant guidelines, expert consensus and latest literature, which has covered the basic requirements, application scope, pre-testing service, testing procedure, report interpretation, genetic counseling, and limitations for this technology.

Objective:To explore the application of triplet-primer PCR (TP-PCR) for the genetic testing and prenatal diagnosis in patients with Myotonic dystrophy type 1 (DM1).Methods:A total of 60 individuals from 48 pedigrees undergoing genetic testing at the Genetic and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University from May 2018 to October 2022 were selected as the study subjects. TP-PCR combined with capillary electrophoresis was applied to determine the number of CTG repeats of the DMPK gene, and prenatal testing was provided to four DM1 pedigrees. This study was approved by Medical Ethics Committee of the First Affiliated Hospital of Zhengzhou University (Ethics No. KS-2018-KY-36). Results:A total of 52 DM1 patients were detected, mostly with muscle weakness, muscular atrophy and myotonia as the initial symptoms, along with typical myotonic potentials. Some patients also had abnormalities of other systems. The number of abnormal CTG repeats of the DMPK gene was > 50, whilst the number of CTG repeats on the normal allele had ranged from 5 to 18. The number of the most common normal CAG repeats was 6 (30.77%, 16/52). Among the four DM1 pedigrees undergoing prenatal diagnosis, one fetus was healthy, whilst three fetuses were found to have abnormal CTG repeats (> 50 times) and diagnosed with DM1. Conclusion:TP-PCR can diagnose DM1 patients with speed and accuracy. However, this method cannot accurately determine the number of CTG repeats when it exceeds 50.