A paternity case with three genetic incompatibilities between father and child due to maternal uniparental disomy 21 and a mutation at the Y chromosome.

A parentage case is described that revealed a potentially erroneous exclusion from paternity in three systems, two on chromosome 21 and one on chromosome Y. Follow-up tests, especially of chromosome 21, were subsequently performed. Actually, the child's chromosome 21 showed alleles of maternal but not of paternal origin being consistent with a maternal uniparental disomy of chromosome 21. The third genetic incompatibility was observed at the Y chromosome and attributed to a usual one-step de novo mutation. This case is emphasizing the (generally adopted) requirement that an exclusion from paternity must not be based on the absence of paternal alleles at genetic systems all located on the same chromosome. In fact, the need for extended typing programmes is demonstrated.

[Paternity testing and civil affairs]. / Empreintes génétiques et affaires civiles.

Paternity testing is based on the genetic analysis of human polymorphism markers. Recently, studies of short tandem repeats (STR) after DNA amplification have led to increased standardisation and performance of the tests and have become the reference method. Thus, the results expressed in terms of probability achieve a high level of certitude, for example the probability of paternity can exceed 99.999%. All these analyses, which are performed according to a specific quality assurance program, are a very useful tool for courts of justice.