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Objective:To analyze the phenotypes and genetic etiology of microcephaly- seizures-development delay (MCSZ) syndrome.Methods:The patient was diagnosed with MCSZ syndrome in June 2018 at Shenzhen Maternity and Child Healthcare Hospital. She was the couple's first child, and the mother conceived a second child in 2020. The clinical data of the proband were retrospectively analyzed, and the bioinformatics analysis and whole-exome sequencing (WES) were performed on the proband and her parents to identify the pathogenic variants, which were further validated using Sanger sequencing. The prenatal genetic diagnosis of the second fetus was performed following the molecular diagnosis of the proband was confirmed. The clinical manifestations and pathogenesis of MCSZ syndrome were summarized by reviewing related literature.Results:(1) Case report: The patient, an eight-month-old girl, was admitted to our hospital due to microcephaly and repeated seizures. Another clinical characteristic was mental retardation. Auditory evoked potential detected moderate impairment of the left auditory nerve pathway. WES showed a compound heterozygous variation in the PNKP gene of the proband. Moreover, the pathogenic variation, c.199-10_203delinsTCTGAGGGGT, was inherited from the father, and the likely pathogenic variation, c.1505C>T(p.P502>L), was inherited from the mother, which was both de novo mutations. The compound heterozygous variation in the PNKP gene was considered genetic etiology based on the genetic testing and clinical features. Prenatal diagnosis showed that the second fetus did not inherit the PNKP gene variants from the parents and the couples chose to continue the pregnancy. A girl was born, and her psychomotor development and occipitofrontal size circumference were normal at 13 months old. (2) Literature review: 39 MCSZ syndrome cases were retrieved, including the present case and 38 cases from 12 relevant literature. The clinical characteristics were microcephaly (91.7%, 33/36), seizures (88.2%, 30/34), development delay (96.4%, 27/28), hyperactivity (25.6%, 9/39), gastroesophageal reflux (10.3%, 4/39), and hearing loss (7.7%, 3/39). Most patients' first onset of epilepsy was in infancy (96.3%, 26/27). Cranial MRI examination showed brain dysplasia in 31 cases (91.2%, 31/34). Conclusions:When the fetal head circumference is smaller than normal and is progressively reduced combined with postnatal microcephaly, epilepsy, developmental retardation, hyperactivity disorder, gastroesophageal reflux, and hearing loss, MCSZ syndrome should be considered. The prognosis varies widely, and genetic testing facilitates the early diagnosis and genetic counseling of MCSZ syndrome.
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Two pedigrees are reported here including two siblings and a boy who were diagnosed with Aicardi-Goutières syndrome type 3 (AGS3) caused by compound heterozygous variation of RNASEH2C gene. Prenatal gene diagnosis was performed when their mothers were pregnant again. All three cases presented with epilepsy, microcephaly, muscular hypertonia and severe language, motor and mental retardation. In pedigree 1, genetic analysis showed compound heterozygous variants of c.194G>A (p.Gly65Asp) and c.434G>T (p.Arg145Leu) in the RNASEH2C gene of proband 1 and her younger brother, which were inherited from their mother and father respectively. While in pedigree 2, c.194G>A(p.Gly65Asp) and c.227C>T(p.Pro76Leu) compound heterozygous variants in the RNASEH2C gene were found in proband 2, which were inherited from his father and mother, respectively. Diagnosis of AGS3 was confirmed in these three cases based on their medical history and the testing results. The mothers from the two families underwent prenatal diagnosis in their subsequent pregnancy, and the variation only inherited from the mothers was detected, suggesting that the two fetuses are carriers. Both families chose to continue the pregnancy and delivered at full-term. No growth or development abnormalities were reported in the children during a one-year follow-up.
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Objective:To summarize the genetic diagnosis of two fetuses with clinically suspected Bardet-Biedl syndrome (BBS) and to provide information for genetic counseling and prenatal diagnosis of BBS.Methods:Case one had prenatal care on October 2018 in Shenzhen Maternity and Child Healthcare Hospital and was clinically suspected of fetal BBS as bilateral renal parenchyma echo enhancement as well as polydactyly (six toes on each foot) were shown on ultrasonic examination at 18 +1 gestational weeks. Case two was another suspected fetal BBS for enlarged kidneys with echo enhancement as well as polydactyly (six fingers and toes on each hand and foot) on ultrasonic examination at 26 +4 gestational weeks on August 2016 and the parent requested for termination. Parents of both cases requested for genetic analysis. Amniotic fluid sample was obtained in case one at 19 +6 weeks through amniocentesis, and umbilical cord specimen of case two and peripheral blood samples of the parents were collected. Genetic analysis of the fetuses and their parents was performed using exon capture and next-generation sequencing and the results were validated using Sanger sequencing. Results:Case one carried paternally inherited c.718G>A (p.Gly240Ser) (possible pathogenic) mutation and maternally inherited c.497C>A(p.Ala166Asp) (possible pathogenic) mutation in BBS7 gene. While one paternally inherited mutation c.1002delT(p.N335Ifs*47) (pathogenic) and one maternally inherited heterozygous mutation c.728G>A (p.Cys243Tyr) (possible pathogenic) were identified in BBS7 gene of case two. The three unreported missense mutations were predicted to be harmful by bioinformatics software and the mutation sites were conservative after comparing with multiple species-based protein sequences. Conclusions:Enlarged kidneys with echo enhancement and polydactyly may indicated a BBS fetus caused by BBS7 gene mutation. Whole exome sequencing could provide relevant information for prenatal diagnosis and genetic counseling in these cases.