Without more information on the specific genes and alleles involved, it is not possible to say the first child of a couple with the genotypes AA and AS would be. The child's genotype would depend on the specific combination of alleles inherited.
If AA and AS marry, their first child will have the genotype Aa (heterozygous)....................................................................................................................
The genotype of the child will depend on the genotype of the parents. If both parents are AA and AS, the child may have a genotype of AA, AS, or SS. Each of these genotypes has a 25% chance of occurring.
AA marries an AS. You'll end up with kids with AA and AS which is good. But sometimes if you're not lucky all the kids will be AS which limits their choice of partner. AS and AS should not marry, there is every chance of having a child with SS