Holoprosencephaly (HPE) is a congenital defect of the brain, median structures, 
and face resulting from an incomplete cleavage of the primitive brain during 
early embryogenesis. The authors report a case of trisomy 13 syndrome diagnosed 
at prenatal follow up. The preterm newborn lived only 5 hours, and died because 
of severe respiratory failure. The autopsy findings disclosed facial, skull, 
limbs, cardiac, and cerebral malformations. Among the latter, the presence of 
alobar HPE, the central theme of this report, was evident. The most common 
nonrandom chromosomal abnormality in patients with HPE is trisomy 13. The most 
severe variant, namely alobar HPE, is shown in this case report. Discussion on 
this severe anomaly, along with the case report with details of Patau's 
syndrome, is the goal of this report.