What is the usual minimum set of family members required to assign the "a" and "c" patient haplotypes?

To determine the "a" and "c" patient haplotypes, the most practical and effective approach involves examining direct parental contributions, which is why having the patient and their mother is essential. Haplotype assignment focuses on analyzing the alleles inherited from both parents, as these alleles combine to form the haplotypes.

When only the patient and their mother are available for testing, it is possible to infer the inherited haplotypes from the mother's genotype. The mother's contribution reveals essential information about at least one part of the genetic makeup of the patient—the alleles the patient inherited from her.

While involving other family members, such as siblings or uncles, might provide additional context or confirmatory data regarding the haplotypes, they are not as pivotal as the direct parental connection when establishing the haplotypes. Therefore, testing the patient along with their mother suffices to assign the “a” and “c” haplotypes accurately.