Table 1.

The A1AT alleles and their effects

Allele	Genetic change	Serum A1AT levels μM (Less than 11 = deficient)	Effects
M	Normal	Homozygous (MM): 20–48	Normal
S	Glu246Val	Homozygous (SS): 15–33	Mild plasma deficiency Not clinically significant usually No hepatocellular aggregation
Z	Glu342Lys	Heterozygous (MZ): 12–35 Heterozygous (SZ): 8–19 Homozygous (ZZ): 2.5–7	Carrier Deficient Most significant deficiency Associated with emphysema and liver disease Intra-hepatocellular polymerization key feature
Siiyana	Ser53Phe		Severe plasma deficiency Intra-hepatocellular polymerization
Mmalton	ΔPhe52		Severe plasma deficiency Intra-hepatocellular polymerization Next to Z allele, most frequently associated with liver disease
I	Arg39Cys		Rare Mild plasma deficiency Intra-hepatocellular polymerization
Null		Homozygous: 0	Complete plasma deficiency No polymerization Not associated with liver disease