Prenatal diagnosis of holoprosencephaly associated and proboscis in a fetus with de novo deletion 18p

Objective Holoprosencephaly (HPE) is the most common forebrain developmental anomaly in humans with prevalence of 1/ 16, 000 in live borns that results from a failure of prosencepholon cleavage. In most of the cases, due to defective primordial mesenchyme, facial anomalies are observed like cyclopia, proboscis, median or bilateral cleft lip/palate in severe forms, ocular hypotelorism or solitary median maxillary central incisor in minor forms. The etiology of HPE is heterogeneous and complex, it can result from environmental factors, chromosomal aberrations such as trisomy 13, 18, 21, triploidy or other genetic defects. Chromosomal aberrations are responsible for 25-40% of all HPE cases. The most distal segments of 18p contains the critical region of HPE and 18p11. 3 region includes TGIF1(HPE4) gene that is associated with HPE phenotypes. 10% of patients carrying a 18p deletion present HPE. In this report, we present severe HPE phenotype with deletion 18p11. 2.