Which test is usually the first to be performed to exclude parentage or paternity?

The first test typically performed to exclude parentage or paternity is ABO and Rh testing. This test provides initial information about blood types, which can help determine if potential parents share compatible blood types with a child. For instance, if the blood types of the alleged father and child are incompatible, this can quickly indicate that paternity is unlikely, making it a useful first step in exclusion.

ABO blood typing is straightforward and can yield results relatively quickly compared to more complex tests. While DNA testing is definitive for determining paternity, it is more resource-intensive and often performed later in the processes of parentage testing. Blood type matching serves a similar function, but it is generally considered part of the broader context of ABO and Rh testing.

Chromosome analysis is also more complex and typically not the first step in establishing or excluding parentage compared to the simpler ABO and Rh test. Thus, the selection of ABO and Rh testing as the initial step reflects its efficiency and effectiveness in providing critical initial data in parentage cases.