The father could be:
A.	A+, A-, or O-
B.	A+, A -, AB+, or AB- Dr. Hallick's reply: The father could be type A or type AB. The types that can be ruled out for the father are type O and type B. The father must be the source of the A allele of the child. The Rh factor information doesn't discriminate potential fathers of the child. Even though the child is Rh-, it is not necessary that either parent be Rh-. The father of the child could be either Rh+ (heterozygous with one Rh+ allele and one Rh- allele) or Rh- (homozygous with two recessive Rh- alleles). When the mother is Rh- and the father is Rh+ (heterozygous with one Rh+ allele and one Rh- allele), there is a 50% probability for an Rh+ child and a 50% probability for an Rh- child. When the mother is Rh- and the father is Rh-, as in the case of your own family, then all children (all of your siblings) will be Rh-. Once again, if it is important to have correct and highly discriminating information about paternity, my advice would be to explore the possibility of a DNA-based paternity test. Although I cannot personally endorse any particular testing company, you may wish to visit the web page of a paternity lab at http://www.gentestlabs.com/
C.	B+, B-, or O-

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