[Prenatal phenotype and genetic analysis of a fetus with Fibrochondrogenesis 1 due to compound heterozygous variants of COL11A1 gene].

OBJECTIVE: To explore the genetic etiology of a fetus with short limbs identified by prenatal ultrasonography. METHODS: A fetus detected with short limb malformations at Shengjing Hospital Affiliated to China Medical University on October 25, 2021 was selected as the study subject. Prenatal ultrasound and post-abortion imaging were carried out to determine the phenotypic characteristics of the fetus. Amniotic fluid sample of the fetus and peripheral blood samples of its parents were collected. Following extraction of genomic DNA, whole-exome sequencing was carried out. Candidate variants were verified by Sanger sequencing. Online software was used to predict the structural changes of the mutant proteins. RESULTS: Prenatal ultrasound showed that the fetus had a small bell-shaped thorax, markedly shortened limbs, flat midface, a small nose with anteriorly tilted nostrils, and a small mandible. Post-abortion CT showed typical short and wide fetal ribs, cupped metaphyses at both ends, short long bones with wide metaphyses, resulting in a dumbbell-shaped appearance and curved thoracic vertebrae. Whole-exome sequencing revealed that the fetus had harbored compound heterozygous variants of the COL11A1 gene, namely c.2251G>T and c.3790G>T, both of which were predicted to alter the important Gly-X-Y structure of collagen protein. Sanger sequencing confirmed that the variants were respectively inherited from its parents. CONCLUSION: A rare fetus with Fibrochondrogenesis type 1 due to compound heterozygous variants of the COL11A1 gene has been diagnosed. Above finding has enabled genetic counseling and reproductive guidance for this family.

[Clinical characterization and genetic testing for a patient with creatine deficiency syndrome 1].

OBJECTIVE: To explore the genetic basis for a child affected with cerebral creatine deficiency syndrome 1 (CCDS1). METHODS: High-throughput sequencing was carried out to screen pathogenic variant associated with the clinical phenotype of the proband. The candidate variant was verified by Sanger sequencing. RESULTS: High-throughput sequencing revealed that the proband has carried heterozygous c.327delG variant of the SLC6A8 gene, which was verified by Sanger sequencing.Neither parent was found to carry the same variant. CONCLUSION: The de novo heterozygous c.327delG variant of the SLC6A8 gene probably underlay the CCDS1 in this child.

[Clinical feature and genetic analysis of a fetus with autosomal recessive polycystic kidney disease].

OBJECTIVE: To explore the genetic etiology of a fetus with autosomal recessive polycystic kidney disease (ARPKD). METHODS: Prenatal ultrasonography has revealed oligohydramnios and abnormal structure of fetal kidneys. After careful counseling, the couple opted induced abortion. With informed consent, genomic DNA was extracted from the muscle sample of the abortus and peripheral blood samples of the couple. High throughput whole exome sequencing was carried out to detect potential variants in relation with the disease. Suspected variants were verified by Sanger sequencing. RESULTS: Prenatal ultrasound revealed increased size of fetal kidneys, with multiple hyperechos from the right kidney, and multiple hyperechos with anechoic masses within the left kidney. DNA sequencing revealed that the fetus has carried heterozygous variants of the PKHD1 gene, including c.7994T>C inherited from its father, and two heterozygous variants of the PKHD1 gene c.5681G>A from its mother. CONCLUSION: The compound heterozygous c.7994T>C and c.5681G>A variants of the PKHD1 gene probably underlay the pathogenesis of ARPKD in this fetus. Above results can provide guidance for subsequent pregnancies of the couple.