Third trimester diagnosis of a compound heterozygous QARS1 mutation based upon microcephaly and abnormal placenta.

Objectives: This case aims to highlight the challenges healthcare providers and parents are faced with upon the emergence of fetal anomalies in the third trimester, emphasizing the pivotal role of trio exome sequencing in informed decision-making. Case presentation: A 39 year old women, Gravida II para I, was referred at 30 + 6 weeks of gestation for suspected fetal growth restriction, oligohydramnios, and abnormal placental features. Initial scans had revealed fetal head measurements and cerebellum in the lower normal range. Following further investigation via amniocentesis, fetal MRI, and trio exome sequencing, a compound heterozygous QARS1 mutation was identified. This gene is crucial for brain development. The MRI at 34 weeks confirmed microcephaly and abnormal gyration patterns corresponding to a development stage of 29 weeks. Genetic counseling was provided to the parents, who ultimately decided on late termination of the pregnancy at 34 + 5 weeks. The process was managed with medical support, ensuring psychosomatic and pastoral care for the parents. Conclusions: This case highlights the necessity for detailed and continuous prenatal assessments even amid initially mild fetal anomalies. The identification of the QARS1 mutation late in pregnancy underscores the potential impacts of rare genetic disorders on fetal development and necessitates comprehensive genetic counseling and ethical decision-making for parents and healthcare providers. This case emphasizes the critical role of advanced genetic testing in identifying conditions that significantly influence perinatal management and parental choices.