Why Alpha-1 Antitrypsin Matters to a Healthier Baby Population

• Mass about 52 kDa; 394 amino acids
• Encoded by SERPINA1 on chromosome 14
• Classic serpin "mousetrap" inhibitory mechanism
• Reactive center loop (RCL) Met358-Ser359
• Exosite residues include Glu199, Asp202, and Glu204

Approximate second-order association rates (M^-1 s^-1):

• Neutrophil elastase (NE): about 6.5 x 10^7
• Proteinase 3 (PR3): about 8.1 x 10^6
• Cathepsin G (CG): about 4.1 x 10^5

AAT prefers NE among these targets. AAT also binds IL-8 and can blunt neutrophil chemotaxis.

The common severe Z allele is Glu342Lys. About 85% of Z-AAT is retained in hepatocyte endoplasmic reticulum. That retention drives gain-of-function liver injury while low circulating AAT drives loss-of-function lung and tissue protease risk.

• Birth brings a neutrophil surge
• Enzyme abnormalities peak in infancy for many Pi*ZZ infants
• Growing lung elastin architecture is forming while protease balance is still being set

Identification at birth lets families remove second hits (especially smoke exposure), start liver protocols when indicated, and join registries before irreversible injury accumulates.

A practical program looks like CF-style newborn screening, not a drug mandate:

1. Dried-blood-spot screening with reflex genotype
2. Counseling capacity (the Swedish program documented parental distress when counseling was thin; that is an implementation requirement, not a reason to stay blind)
3. Liver follow-up protocol for severe genotypes
4. Second-hit removal (smoke-free homes, infection vigilance with clinicians)
5. Cascade testing of relatives
6. Registries that feed research and emerging liver RNAi or gene-therapy readiness

• Add Alpha-1 to the newborn blood panel
• Children and cancer risk
• What is Alpha-1 Antitrypsin Deficiency
• AATD diagnosis and testing

Educational content and advocacy only. Not a diagnosis or treatment plan. Work with your clinician for personal medical decisions. Adult labeled uses of plasma AAT do not include routine neonatal augmentation or childhood-cancer prevention.