A rare genetic gender anomaly identified in a paternity case presenting AMEL-Y dropout

Abstract

Abstract The examination of different sets of sex markers in view of gender determination may seem a routine and yet, no forensic geneticist is exempt from dealing with challenging cases on this issue, even if genetic anomalies related to gender occur rarely. We report a AMEL-Y dropout case revealed on the occasion of a paternity investigation, which proved to be a rare, 46,XX (SRY+) male syndrome, also known as de la Chapelle syndrome. The objective of our case report is to highlight the importance of forensic PCR kits to elucidate anomalies related to gender and overcome the problems related to a wrong genetic gender determination in paternity testing or human identification. The subject is a 36-year-old male requesting a paternity test because he was having doubts related to his 2 year-old child born during his marriage. The standard testing results performed on 16 STRs indicated an exclusion from paternity of our male subject who additionally exhibited an AMEL-Y dropout. We further investigated the male sample using a combination of PCR kits (Y-STRs, X-STRs, Amelogenin and SRY gene) and were able to identify the SRY gene, the loss of the major part of the Y-chromosome, except of a small region surrounding the SRY gene, and the presence of two X-chromosomes. Thus, we finally characterized the AMEL-Y anomaly as being a 46,XX male syndrome. Some basic facts related to the frequency, ethiopathology and diagnosis of this syndrome are reviewed and discussed. This study also represents the first reported Amelogenin dropout case detected in the Romanian population.