Unexpected perinatal death caused by an occult MTM1 mutation: a case report.

Background: Genetic mutations can lead to miscarriages, perinatal deaths, and abnormalities in fetal development. Sometimes, the regular prenatal test cannot identify some rare diseases, but whole-exome sequencing can be performed. Whole-exome sequencing testing is not a routine prenatal test unless there is a family history or a history of adverse pregnancy due to a genetic disorder. Case presentation: We reported a case of stillbirth caused by a rare genetic disease, secondary to an MTM1 gene mutation. It was found to have no abnormality during childbirth; even electronic fetal monitoring showed no signs of fetal distress. However, delivery concluded with a stillborn birth, and the offspring having no crying, poor muscle tone, and pale skin. Due to the unclear cause of stillbirth, the patient requested further diagnostic genetic testing to identify a cause. The MTM1 gene hemizygous variant was detected by whole-exome sequencing. Conclusion: Stillbirth due to genetic mutations may not be detected by non-invasive prenatal testing or chromosome copy number variant analysis. Broad Next-Generation Sequencing, such as whole-exome sequencing, has the potential to identify genetic causes that are missed by non-invasive prenatal testing or chromosomal microarray. The indications for the whole-exome sequencing test for pregnant women may need further discussion.