GO ahead with the proposed marriage, if you like her.
Blood groups do not determine possibility of disability
for your future child.
If you marry a girl with any negative( A-ve. B-ve,AB-ve or O-ve ) blood group and your first child is positive blood group, then there is possibility of disease to your second child. But this can be prevented by proper treatment after first pregnancy
About the ' cases before where, when the child is around 10 years these defects and disabilities come out' that you mention , did this occur in your relatives?
In that case some genetic disease is a possibility ( unrelated to blood group ) and you may get an opinion from a clinical geneticist.
Always better to avoid consanguineous marriage ( marriage with blood relatives)