I have a table, sort of like this:
ID | Chromosome | Locus | Symbol | Dominance | =============================================== 1 | 10 | 2
This may work for you:
select t1.* from table t1 join (select t2.Chromosome, t2.Locus from table2 group by t2.Chromosome, t2.Locus having count(*) > 1) u on u.Chromosome = t1.Chromosome and u.Locus = t1.Locus