Not applicable
Performed Weekly.
To confirm the basis of an apparent alpha-1-antitrypsin deficiency and to assess the need to undertake family studies.
MM phenotype is the normal pattern associated with normal serum AAT level. It is found in about 82% of the Caucasian population. MS is a common variant which has no clinical effect.
The Z allele is the most common type that causes clinical effects of AAT deficiency especially in homozygous form (ZZ). ZZ homozygotes have significantly low AAT level in blood (unable to be secreted from liver to blood). These patients are at risk of early onset emphysema accelerated by smoking. They are also at risk for neonatal hepatitis or early onset adult liver cirrhosis (with earlier presentation in alcoholics). MZ heterozygotes have a slight increased risk of emphysema especially in smokers. SZ heterozygotes in general have an AAT level somewhere between MZ and ZZ. SZ heterozygotes carries an intermediate risk for early onset emphysema accelerated by smoking and earlier onset adult cirrhosis.
Rarely, a "MM" phenotype can still carry an increased risk as some M variants either in homozygous or heterozygous form are associated with increased risk for emphysema or liver disease. A hint for the presence of these M variant alleles is a suppressed serum AAT level below lower reference limit. It is thus strongly advisable that AAT phenotype should be interpreted in conjunction with patient's serum AAT level collected at a time when patient is not in an acute inflammatory state.
Reference:
Dahl et al. Ann Intern Med 2002;136:270-279
Am J Respir Crit Care Med 2003; 168:818-900 American Thoracic Society / European Respiratory Society statement: Standards for the diagnosis and management of individuals with alpha-1 antitrypsin deficiency
Ferrarotti I Prevalence and phenotype of subjects carrying rare variants in the Italian registry for alpha 1 antitrypsin deficiency J Med Genet 2005; 42:282-287
Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.
If the query concerns a specific patient please include the NHI number in your email.
If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).
Individual chemical pathologists may be contacted but will not be available at all times.
After-hours : contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.
Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402
Dr Cam Kyle: CampbellK@adhb.govt.nz ext 22052
Dr Weldon Chiu: WeldonC@adhb.govt.nz ext. 23427
Dr Campbell Heron: CHeron@adhb.govt.nz ext. 23427