Related Experiment Video
Updated: Aug 14, 2026
Biochemical Measurement of Neonatal Hypoxia
Published on: August 24, 2011
Molecular confirmation of alpha 1-antitrypsin genotypes in newborn dried blood specimens
W C Spence1, J E Morris, K Pass
1Genetics and IVF Institute, Fairfax, Virginia 22031-4609.
Insights
Newborn screening identified three infants with alpha-1 antitrypsin (alpha 1AT) deficiency, a genetic disorder linked to lung and liver disease. This study developed novel genetic methods for accurate alpha 1AT deficiency detection in newborns.
Area of Science:
- Genetics
- Biochemistry
- Public Health
Background:
- Alpha-1 antitrypsin (alpha 1AT) deficiency is a common hereditary disorder in Caucasians.
- Alpha 1AT deficiency increases the risk of early-onset chronic obstructive pulmonary disease and childhood liver dysfunction.
- The PiS and PiZ variants are the most common deficiency alleles, caused by single base-pair substitutions.
Purpose of the Study:
- To develop and implement reliable screening methods for alpha 1AT deficiency in newborns.
- To determine the incidence of alpha 1AT deficiency in a newborn population in New York State.
Main Methods:
- Dried blood specimens (DBS) were screened for alpha 1AT activity using a fluorometric elastase inhibition assay.
- Alpha 1AT deficient specimens underwent phenotyping via agarose isoelectric focusing.
- Genotypic confirmation utilized PCR amplification from DBS with novel restriction fragment length polymorphism (RFLP) analysis for S and Z mutations.
Main Results:
- Of 11,081 newborns screened, three PiS neonates were detected.
- All identified PiS infants were Caucasian.
- The estimated incidence of alpha 1AT deficiency was 1:2019 in Caucasians and 1:3694 in the general New York State population.
Conclusions:
- Novel RFLP methods enable accurate genetic detection of alpha 1AT deficiency directly from DBS.
- Newborn screening for alpha 1AT deficiency is feasible and identifies affected infants for early intervention.
- The study provides incidence data for alpha 1AT deficiency in a large newborn cohort.
Abstract:
Deficiency of alpha 1-antitrypsin (alpha 1AT), a common hereditary disorder of Caucasians, is associated with an increased risk for early-onset chronic obstructive pulmonary disease and childhood liver dysfunction. The two most common deficiency variants, PiS and PiS, are both single base-pair substitutions causing amino acid modifications, although neither mutation creates or destroys a naturally occurring restriction site. Dried blood specimens (DBS) submitted to the New York State Department of Health for mandated newborn screening tests were tested for alpha 1AT activity using a fluorometric elastase inhibition assay. A second DBS from specimens determined to be alpha 1AT deficient was phenotyped on an agarose isoelectric focusing gel. Genotypic confirmation was performed by amplifying, directly from a DBS, the regions of the DNA containing the S and Z mutation. The Z mutation was analyzed with a modified primer designed to create an artificial restriction site in the normal allele. TaqI digestion produces two bands, a 157- and a 22-bp fragment. The single base substitution in PiS individuals eliminates this TaqI restriction site, thus showing the same 179-bp fragment before and after digestion. A primer mismatch placed close to the S mutation creates a restriction site in the normal allele, producing a 100-bp product after TaqI digestion. The restriction site is abolished in individuals that carry the S mutation, with a 121-bp product observed before and after digestion. Of 11,081 specimens screened, 3 PiS neonates, all Caucasian, were detected by these methodologies for an estimated incidence of 1:2019 in the Caucasian or 1:3694 in the general population in New York State.(ABSTRACT TRUNCATED AT 250 WORDS)
