I have a table, sort of like this:
ID | Chromosome | Locus | Symbol | Dominance | =============================================== 1 | 10 | 2
The problem is GROUP BY - if you group results by Locus, you only get one result per locus.
GROUP BY
Try:
SELECT * FROM Genes WHERE Locus = '3' AND Chromosome = '10';
If you prefer using HAVING syntax, then GROUP BY id or something that is not repeating in the result set.
HAVING
GROUP BY id