Non-immune hydrops fetalis is associated with bi-allelic pathogenic variants in the MYB Binding Protein 1a (MYBBP1A) gene.

Non-immune hydrops fetalis (NIHF) is a rare entity characterized by excessive accumulation of fluid within the fetal extravascular compartments and body cavities. Here we present two intrauterine fetal demises with NIHF presenting with oligohydramnios, cystic hygroma, pleural effusion, and generalized hydrops with predominance of subcutaneous edema. The fetuses also presented with ascites, severe and precocious IUGR and skeletal anomalies. Whole exome sequencing was applied in order to screen for a possible genetic cause. The results identified biallelic variants in MYBBP1A in both fetuses. A previous report described another case with a similar phenotype having compound heterozygous variants in the same gene. The protein encoded by MYBBP1A is involved in several cellular processes including the synthesis of ribosomal DNA, the response to nucleolar stress, and tumor suppression. Our functional protein analysis through immunohistochemistry indicates that MYBBP1A is a gene expressed during fetal stages. Altogether, we concluded that MYBBP1A is associated with the development of hydrops fetalis. More cases and further studies are necessary to understand the role of this gene and the mechanism associated with NIHF.

Prenatal Diagnosis of Acromelic Frontonasal Dysostosis.

Acromelic frontonasal dysostosis (AFND; MIM #603671) is a rare autosomal dominant genetic disorder caused by a heterozygous mutation in the ZSWIM6 (KIAA1577) gene located at chromosome 5q12.1. It is phenotypically characterized by frontonasal malformation with hypertelorism, telecanthus, nasal clefting or bifid nasal tip, wide fontanels and sutures, brachycephaly, and cleft palate. The patients also present with central nervous system malformations such as encephalocele, agenesis of the corpus callosum, or interhemispheric lipoma. Limb malformations can also be found, including preaxial polydactyly of the feet and sometimes postaxial polydactyly of the hands, talipes equinovarus, or tibia malformations. Here, we present a case of early prenatal diagnosis of AFND with ultrasound and necropsy images which show the phenotypic findings of this syndrome.