[Pathological characteristics and genetic analysis of a stillborn harboring compound heterozygous nonsense variants of TH gene].

OBJECTIVE

To carry out pathological and genetic analyses on a fetus with intrauterine growth restriction and death during second trimester after induced abortion.

METHODS

A fetus undergone induced abortion due to intrauterine growth restriction and death during second trimester at the the Seventh Affiliated Hospital of Sun Yat-Sen University in 2024 was selected as the study subject. Clinical data of the pregnancy were collected. DNA was extracted from tissues from the aborted fetus and peripheral blood samples from its parents. Chromosomal microarray analysis and whole exome sequencing were carried out. Candidate variants were verified by Sanger sequencing. Following abortion, routine autopsy and pathological analysis were conducted. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: KY-2025-334-01).

RESULTS

The aborted fetus was a male and harbored compound heterozygous nonsense variants of the TH gene (c.457C>T/p.Arg153* and c.694C>T/p.Gln232*), for which both parents were heterozygous carriers. Autopsy and pathological analysis revealed that the fetus had pathological features including loose arrangement of myocardial fibers and congestion in the liver.

CONCLUSION

Biallelic null variants of the TH gene may cause heart failure by affecting the development of cardiovascular system, which in turn may lead to intrauterine death. This study has provided new clues for the molecular diagnosis of stillbirth and recurrent pregnancy loss.