Welcome to Belly Belly Beau9 and congratulations on your pregnancy.

The NT test does give a percentage rate for trisomy 21 and most centres give a percentage for 2 other trisomies that are less common.

I am aware of the condition your husband has - this will not affect your NT test.
Basically the NT test is a blood test (free bhcg and PappA) combined with measurement of the nuchal fold and other soft markers.

Wishing you well with your pregnancy.