This study examined the genetic causes of microcephaly detected before birth in 197 fetuses, using multiple testing methods including karyotyping, chromosomal microarray, and whole exome sequencing. Researchers found that nearly half had isolated microcephaly, while the rest had additional features, with chromosomal abnormalities and harmful copy number variants more common in the non-isolated group. Trio whole exome sequencing identified single-gene causes in some cases, including variants in the POGZ gene, which was linked to the microcephaly phenotype. The findings highlight that fetal microcephaly has diverse genetic causes and that combining multiple testing approaches improves the chances of reaching a diagnosis.