Serum amyloid A serum concentrations and genotype do not explain low incidence of amyloidosis in Hyper-IgD syndrome.
BACKGROUND
Hyper-IgD and periodic fever syndrome (HIDS) is an autosomal recessively inherited disorder characterized by recurrent episodes of fever and inflammation. Unlike other chronic inflammatory conditions, amyloidosis is very rare in HIDS. For deposition of amyloid of the AA type, high concentrations of SAA are a prerequisite, together with certain SAA1 gene polymorphisms. The SAA1.1 genotype predisposes for amyloidosis, while SAA1.5 genotype exerts a protective effect.


OBJECTIVE
To determine if SAA concentrations and SAA1 gene polymorphisms could explain the virtual absence of amyloidosis in HIDS patients.


METHODS
We measured SAA and CRP concentrations in serum of 20 HIDS patients during an attack and during the asymptomatic phase. Genotype of SAA1 gene was determined in 60 HIDS patients.


RESULTS
SAA serum concentrations during attacks were very high (median 205 mg/l; range 75-520 mg/l, normal <3.1 mg/l). During attack-free periods 45% of patients still had elevated SAA concentrations. The distribution of the genotype of SAA1 gene in HIDS was similar to healthy controls (SAA1.1 0.41 vs. 0.50 p=0.32).


CONCLUSIONS
Patients with HIDS have high SAA during attacks and show sub-clinical inflammation when asymptomatic. The low incidence of amyloidosis cannot be explained by a predominance of non amyloidogenic SAA related genotypes.
van der Hilst
J C H
JC
Department of General Internal Medicine, UMC St. Radboud, Nijmegen, The Netherlands. j.vanderhilst@aig.umcn.nl
Drenth
J P H
JP
Bodar
E J
EJ
Bijzet
J
J
van der Meer
J W M
JW
Simon
A
A
D000686:Amyloidosis / Q000097:blood* / Q000235:genetics; D015331:Cohort Studies; D010505:Familial Mediterranean Fever / Q000097:blood* / Q000235:genetics; D005838:Genotype; D006801:Humans; D007072:Immunoglobulin D / Q000097:blood*; D015994:Incidence; D000685:Serum Amyloid A Protein / Q000235:genetics* / Q000378:metabolism*
D007072:Immunoglobulin D; D000685:Serum Amyloid A Protein