Microcephaly-seizures-development delay syndrome in a pedigree: genetic analysis and literature review / 中华围产医学杂志

ABSTRACT

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.