Alobar holoprosencephaly associated with a rare chromosomal abnormality Case report and literature review

Rationale: Holoprosencephaly is a structural malformation of the brain that results from the complete or incomplete noncleavage of the forebrain of the embryo into 2 hemispheres. We report a severe case of alobar holoprosencephaly diagnosed at 38 weeks, associated with cebocephaly, microcephaly, and craniosynostosis. Patient concern: The main knowledge added by this case is the late ultrasound diagnosis and chromosomal analysis that revealed a very rare abnormality (45X/46, XX/47, XX) with mosaicism at chromosome 18. Diagnoses: Investigation of the mother revealed nothing remarkable from clinical point of view and on laboratory tests. Ultrasonography identified a fetal biometry appropriate for gestational age, except for the head biometry and abdominal circumference, that were appropriate for less than the fifth percentile. Microcephaly, a large midline monoventricle, absent midlinestructures, cleft lip, cebocephaly (hypotelorism, single-nostril nose), ethmocephaly (hypotelorism, interorbital proboscis) and craniosynostosis, were also present. Fetal magnetic resonance imaging of fetus revealed an absent midline structure, a central monoventricle, abnormal corpus calosum, and abnormal gyri. Interventions: A cesarean section at 38 weeks was indicated for fetal bradycardia and a female baby was delivered, with Apgar score 6, weight 2290g. After birth, the diagnosis of the fetus confirmed holoprosencephaly with facial anomalies and demonstrated repeated tonic-clonic seizure, severe respiratory failure, cyanosis, decreased muscle tone, palor, and apnea. Laboratory examination of the newborn revealed acidosis and a prolonged of prothrombin time. The neonate was treated for severe respiratory distress syndrome, with immediate intubation and resuscitation. Vitamin K, fresh frozen plasma, and antibiotics were also administered. Outcomes: After delivery, exitus of the fetus occurred at 3 days and 18hours due to massive pulmonary hemorrhage. Lessons: We described a case of alobar holoprosencephaly diagnosed at 38 weeks of gestation and associated with a rare chromosomal abnormality (45X/46, XX/47, XX) with mosaicism at chromosome 18. Emotional implications could have been less severe if the patient underwent regular ultrasonography allowing a diagnosis in the first or early second trimester.