Vertebral Bone Density Abnormalities in Fetal Ultrasound: A Distinctive Clinical Sign of Spondylocarpotarsal Synostosis Syndrome MYH3-Related

Abstract

Background

Ultrasound diagnosis of fetal skeletal conditions remains challenging. MYH3 is a gene that encodes the embryonic myosin heavy chain; it is important for skeletal and muscular development and is strongly expressed during fetal development. Variants in MYH3 are involved in distal arthrogryposes 2A and 2B3 and in spondyocarpotarsal synostosis syndrome with contractures and pterygia, contractures of proximal and distal joints, variable spine anomalies and vertebral, carpal and tarsal fusions.

Key Findings

We describe a case in which prenatal ultrasonography detected abnormal bone density in the fetal spine. The fetus showed abnormal spinal segmentation, characterised by demineralisation and lacunar morphological tracts. x-rays and histological examination confirmed the ultrasonographic findings. We describe a unique ultrasonographic phenotype of fetal spine that has not yet been described in the literature. This is likely associated with two MYH3 variants. Therefore, we believe that abnormal spinal segmentation should be considered a relevant ultrasound finding.

Discussion

Fetal ultrasound, together with radiological investigations, clinical examination of the fetal phenotype and histological investigations are essential in directing molecular genetic testing to identify rare diseases. We review the literature and describe a prenatal case with abnormal bone density in the spine. Whole-exome sequencing (WES) analysis in the fetus was performed to explore variants compatible with ultrasound signs.