To investigate the diagnostic features of Meckel-Gruber syndrome(MKS).

The ultrasonographic data, pathological findings and genetic testing results of a fetus with MKS diagnosed prenatally in Department of Ultrasonography, Maternal and Child Health Hospital of Hubei Province on July 5, 2019 were analyzed retrospectively, and the relevant literatures were reviewed.

A 28-year-old healthy Chinese woman presented at the 11^{+ 6} weeks of gestation underwent the first-trimester ultrasound investigation. The ultrasound examination showed interruption of fetal skull hyperechoic ring with protrusion of meninges and cerebral tissue around occipital region, enlarged kidneys with small anechoic and cysts, postaxial polydactyly of double hands and double feet in this fetus, diagnosed as MKS. The pathological examination of the aborted fetus showed occipital encephalocele, postaxial polydactyly, polycystic kidneys and cleft palate. By whole-exome sequencing, two novel heterozygous mutations [c.3688 C>T(p.Arg1230^*), c. 4314+ 1-4314+ 2insT] in the CC2D2A gene were identified. These two mutations had never been described before. Sanger sequencing validated the mutations in the fetus and revealed that they were originated from the father and mother, respectively. These two variants were classified as likely pathogenic mutations (PVS1+ PM2) according to the variation classification criteria and guidelines of American College of Medical Genetics and Genomics (ACMG).

In early pregnancy, MKS is mostly characterized by occipital encephalocele, enlarged kidneys with small pyramidal cysts and postaxial polydactyly. The first trimester of the pregnancy is the earliest and best time for prenatal diagnosis of MKS. High throughput sequencing technology provides important genetic information for the family with fetuses affected by MKS.