BACKGROUND: Prenatal diagnosis of severe bone diseases is challenging and requires complete and precise analysis of fetal anomalies to guide genetic investigation and parental counselling.

CASE REPORT: We report a rare case of Antley-Bixler syndrome prenatally diagnosed at 26 weeks’ gestation by ultrasound and computed tomography in a 28-year-old woman with a history of early termination of pregnancy for “malposition of the inferior limbs”. The prenatal ultrasound scan showed severe femoral bowing and frontal bossing. Taking into account the high probability of a recurrent severe skeletal disorder, a computed tomography (CT) scan was proposed. CT findings revealed bilateral femora deformation, craniosynostosis, severe midface hypoplasia, and radiohumeral synostosis. These anomalies strongly suggested Antley-Bixler syndrome. Sequencing of the POR gene in the fetus and the parents revealed compound heterozygous mutations in exon 9 and intron 7, both inherited from each parent, and this finding allowed genetic counseling.

CONCLUSIONS: The first step in the proper prenatal diagnosis of fetal bone disorders is the precise analysis of ultrasonographic images. However, when a severe fetal inherited disorder is strongly suspected in late mid-trimester, CT may be discussed and usefully contribute to diagnosis and prognosis assessment.

Keywords: Cytochrome P-450 Enzyme System - genetics, Antley-Bixler Syndrome Phenotype - embryology, DNA Mutational Analysis, Diagnosis, Differential, Fatal Outcome, Fetal Diseases - diagnosis, Imaging, Three-Dimensional, Mutation, Pregnancy, Prenatal Diagnosis - methods, Tomography, X-Ray Computed, Ultrasonography, Prenatal