Your genes are inherited from your parents. If you have Alpha-1, you received one Alpha-1 gene from your mother and one Alpha-1 gene from your father. Your siblings may inherit the same genes, or a different set of Alpha-1 genes. Most people identified with Alpha-1 have the ZZ “genotype”. Another common gene for Alpha-1 is the “S” gene. The “M” gene is normal. Figure 1 shows an example of how Alpha-1 can be inherited.
Family Testing Brochure – Alpha-1 Foundation
This condition is inherited in an autosomal codominant pattern. "Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked. In codominance, ... More means that two different versions of the gene may be active (expressed), and both versions contribute to the genetic trait.Genetics Home Reference