Widespread divergence of the CEACAM/PSG genes in vertebrates and humans suggests sensitivity to selection

In mammals, carcinoembryonic antigen cell adhesion molecules (CEACAMs) and pregnancy-specific glycoproteins (PSGs) play important roles in the regulation of pathogen transmission, tumorigenesis, insulin signaling turnover, and fetal–maternal interactions. However, how these genes evolved and to what extent they diverged in humans remain to be investigated specifically. Based on syntenic mapping of chordate genomes, we reveal that diverging homologs with a prototypic CEACAM architecture–including an extracellular domain with immunoglobulin variable and constant domain-like regions, and an intracellular domain containing ITAM motif–are present from cartilaginous fish to humans, but are absent in sea lamprey, cephalochordate or urochordate. Interestingly, the CEACAM/PSG gene inventory underwent radical divergence in various vertebrate lineages: from zero in avian species to dozens in therian mammals. In addition, analyses of genetic variations in human populations showed the presence of various types of copy number variations (CNVs) at the CEACAM/PSG locus. These copy number polymorphisms have 3–80% frequency in select populations, and encompass single to more than six PSG genes. Furthermore, we found that CEACAM/PSG genes contain a significantly higher density of nonsynonymous single nucleotide polymorphism (SNP) compared to the chromosome average, and many CEACAM/PSG SNPs exhibit high population differentiation. Taken together, our study suggested that CEACAM/PSG genes have had a more dynamic evolutionary history in vertebrates than previously thought. Given that CEACAM/PSGs play important roles in maternal–fetal interaction and pathogen recognition, these data have laid the groundwork for future analysis of adaptive CEACAM/PSG genotype-phenotypic relationships in normal and complicated pregnancies as well as other etiologies.Chia Lin Chang, Jenia Semyonov, Po Jen Cheng, Shang Yu Huang, Jae Il Park, Huai-Jen Tsai, Cheng-Yung Lin, Frank Grützner, Yung Kuei Soong, James J. Cai, Sheau Yu Teddy Hs

Spontaneous Cessation of Communicating Flow in a Twin Reversed-arterial Perfusion with Large Acardiac Twin

We report a case of twin reversed-arterial perfusion diagnosed at the gestational age of 17 weeks. Though the acardiac/pump twin abdominal circumference ratio was 1.5, there was no critical Doppler finding of reverse A wave of ductus venosus, polyhydramnios or hydrops of the pump twin at the time of diagnosis, so the patient was regularly followed-up at clinic at 1-week intervals. Two weeks after the diagnosis, the patient requested surgical intervention because she was worried about the risk of heart failure in the pump twin. Fetoscopic guide laser coagulation of the communicating vessels was arranged. On the morning of the operation, cessation of the communicating flow was found, so the operation was cancelled. On the afternoon of the same day, amniocentesis was performed and the pump twin was found to have scalp edema. The patient was followed-up at clinic at 2-week intervals. A healthy female baby was born by vaginal delivery at the gestational age of 36 weeks