In countries where prenatal care is rare and infections often undiagnosed in pregnant women, the neonatal diagnosis of congenital infections, namely parasitic, is crucial for avoiding acute disease and increasing the effectiveness of treatments administered early. To overcome implementation and/or interpretation difficulties of current techniques, a proteomic approach has been patented in our laboratory. It exploits the individual amino acid polymorphism of the CH2 and CH3-CHS from the heavy gamma chain of the immunoglobulin G (IgG), and aims at distinguishing maternal from fetal IgGs in newborns serum samples. The purpose of the study was to bring a molecular validation of these proteomic results by the sequencing of encoding DNA fragments. Ten individual samples (DNA and sera) were selected on the basis of their Gm (gamma marker) allotype polymorphism in order to cover the main immunoglobulin heavy gamma (IGHG) gene diversity. Gm allotypes, reflecting part of this diversity, were determined by a serological method. The IGH locus comprises four functional IGHG genes totalizing 34 alleles referenced in the IMGT® IMGT/GENE-DB database. These genes are at the origin of the four IgG subclasses. The study focused on the nucleotide polymorphism of the CH2 and CH3-CHS constant region. Despite strong sequence homology, four pairs of specific gene amplification primers were designed. Additional primers were identified to perform the subsequent sequencing. The nucleotide sequences obtained were checked for their assignment to a specific IGHG gene. IGHG alleles were then deduced using a home-made decision tree reading of nucleotide sequences. Identical results were found at 95% between IGHG amino acid (AA) alleles determined by mass spectrometry and those deduced from genomics. These results validate the proteomic approach which could be used for a mother-and-child differential IGHG detection in a context of suspicion of congenital infection.