Searching for the needle in the haystack: another candidate needle in autoimmune hepatitis?

Genetic analysis of the HLA region of Japanese patients with type 1 autoimmune hepatitis

BACKGROUND/AIMS

Genetic predisposition to type 1 autoimmune hepatitis (AIH) is linked mainly to HLA-class II genes. The aim of this study is to scan the HLA region for additional genes which may contribute to type 1 AIH susceptibility.

METHODS

We performed association analysis using HLA class I and II alleles and 18 polymorphic microsatellite markers distributed throughout the HLA region. We specifically assessed tumor necrosis factor (TNF)-alpha gene polymorphisms.

RESULTS

The frequencies of HLA-DRB1*0405, DRB4 and DQB1*0401 alleles were significantly higher in AIH patients. The association study revealed the presence of three segments in the HLA region showing significantly low P (Pc) values. The first segment was located around the HLA-DR/-DQ subregion, the second was around the HLA-B54 allele, and the third was around two microsatellites near the TNF gene cluster. However, stratification analysis for the effect of DRB1*0405 eliminated association of the latter two segments. Haplotype D of the TNF-alpha promoter gene polymorphisms was weakly associated with susceptibility, but was found to be not significant after stratification analysis.

CONCLUSIONS

The most influential gene on type 1 AIH pathogenesis in Japanese is the HLA-DRB1. Other genes in the HLA region, including TNF-alpha, have little or no association with type 1 AIH susceptibility.

Severe autoimmune hepatitis first presenting in the early post partum period

BACKGROUND & AIMS

Autoimmune hepatitis (AIH) may run an aggressive clinical course if untreated. The influence of pregnancy on AIH is variable. Both flares in disease activity and remissions, often followed by a post partum flare, are well recognized. In contrast, definite AIH first presenting in the early post partum period has not been reported.

METHODS

We discuss a case series of 5 patients who developed severe AIH within 4 months post partum.

RESULTS

The diagnosis of AIH was definite based on internationally accepted criteria. Liver injury responded to conventional immunosuppressive therapy in all patients. Immune reactivation in the early post partum period may contribute to this entity.

CONCLUSIONS

AIH should be considered in the differential diagnosis of liver dysfunction first presenting in the early post partum period.

Relationship between autoimmune hepatitis and HLA-DR4 and DRβ allelic sequences in the third hypervariable region in Chinese

AIM: To analyze the association of HLA-DRB1 with autoimmune hepatitis (AIH) in patients from China.

METHODS: In 32 patients and 48 healthy controls, polymerase chain reaction amplification with sequence-specific primers (PCR-SSP) was performed to examine the association of certain alleles or polymorphic sequences of HLA-DRB1 with AIH.

RESULTS: HLA-DRB1 typing by PCR-SSP showed that DR4 had a significantly increased frequency among patients with AIH versus healthy control (46.9% versus 20.8%; relative risk = 3.35, P = 0.014). In subtypes of DR4, there was a trend of increase in the gene frequency of DRB1 *0405 in patients with AIH versus healthy controls (21.9% vs 6.3%, P = 0.04, but P_c = 0.08). In addition, a significant increase was found in the alleles frequency encoding QRRAA from the third hyperpolymorphic region of DR4 in the patients with AIH (86.7% of DR4 positive patients vs 40.0% in DR4 positive controls, P = 0.016, P_c = 0.028, RR = 9.75).

CONCLUSION: AIH in Chinese is associated with HLA-DR4. There is a relationship between QRRAA sequence within the third hyperpolymorphic region of the DRB allele and AIH in Chinese.