Context: The deletion of the short arm of the chromosome 13, also known as 13q syndrome, is an extremely rare chromosomal disorder. Clinical manifestations include retinoblastoma, brain anomalies, mental and growth retardation, as well as renal, cardiac, gastrointestinal, facial, lip and digital defects. Antenatal diagnosis is suspected when the presence of anomalies is detected and it is confirmed through chromosome analysis.
Case report: We reported a case of the 13q syndrome which was diagnosed in the 23rd week of gestation in a fetus with holoprosencephaly and we discussed the two and three-dimensional ultrasonography main findings. This is the first case reported in MEDLINE involving the use of three-dimensional ultrasonography in the structural anomalies evaluation of this syndrome.