HL-A antigen frequencies in myeloma

The Association of HLA Class 1 and Class 2 Antigens with Multiple Myeloma in Iranian Patients

Objective: Multiple myeloma (MM) is a B-cell malignancy characterized by the clonal proliferation of malignant plasma cells. According to results of some studies, it has been suggested that the HLA class 1 and 2 genes have susceptibility effects on MM. Studies of different populations have reported different HLA class 1 and 2 alleles that affect MM. In this study, we assessed the association of HLA class 1 and class 2 antigens with MM in Iranian patients.

Materials and Methods: We performed a case-control genotyping study with 105 Iranian MM patients that were selected from the bone marrow transplantation department of Taleghani Hospital and 150 controls using single specific primer-polymerase chain reaction with the HLA-Ready Gene ABDR Kit.

Results: Our results demonstrated that 21% of patients versus 12% of controls and 11% of patients versus 3% of controls carried HLA-A*03 and HLA-B*18, respectively. The MM patients had a significant increase in the frequency of HLA-A*03 and HLA-B*18 alleles in comparison to control subjects (p=0.039, OR=2.057 and p=0.013, OR=3.567, respectively).

Conclusion: Our findings suggested that the HLA-A*03 and HLA-B*18 alleles have significant susceptibility effects on MM in the Iranian population. However, compared to other populations, the above-mentioned alleles had different statuses. Since there are not many studies evaluating and calculating this association among ethnic groups, further studies among other populations are needed to explain the exact association of the HLA genes with MM.

Inherited predisposition to multiple myeloma

Multiple myeloma (MM) is the second most common hematologic malignancy in the United States, after non-Hodgkin lymphoma. Family pedigree analyses of high-risk families, case-control studies and racial disparities in disease incidence all point to a potential inherited predisposition to MM. Genome-wide association studies (GWASs) have identified susceptibility loci in a number of cancers and such studies are currently underway in MM. To date, GWASs in MM have identified several potential regions of interest for further study on chromosomes 3p22, 7p15.3, 8q24 and 2p23.3. In addition, several targets of paraproteins (so called 'paratargs') in MM have been identified. Hyperphosphorylation of the paratarg protein, which is inherited in an autosomal dominant manner, appears a common mechanism underlying the antigenicity of these proteins. One particular protein, hyperphosphorylated paratarg-7 (pP-7) is a common target in persons with myeloma and has also been identified in affected members of several high-risk MM families. It appears that the frequency of pP-7 as an antigenic target may be particularly high in African American patients with MM, which could be part of the explanation for observed racial disparities in the incidence of MM. In this review we focus on available data in the area of inherited predisposition to MM, and highlight future research directions.

Familial Waldenstrom's macroglobulinemia

The etiology of Waldenstrom's macroglobulinemia (WM) is unknown. A possible role for genetic factors has been suggested by reports of familial clustering of WM. However, it is not yet possible to define the proportion of all WM that occurs in the familial setting. Review of the data on the 12 families published since 1962 suggests that familial WM may differ from sporadic disease in certain respects. Among these families, there is a pronounced occurrence of a variety of immunologic abnormalities in the relatives of WM cases. Notably, the prevalence of IgM monoclonal gammopathy (IgM MG) in first-degree relatives of WM cases was reported to be as high as 6.3%, representing a 10-fold increase relative to general population estimates. IgM MG has been shown to progress to WM at a rate of approximately 1.5% per year in a large case series; whether this rate of progression is altered in familial WM is unknown. Although limited by small numbers and a lack of systematic ascertainment and evaluation, these data are intriguing and provide a compelling basis for further study and systematic investigation of WM in families.

HLA class I and class II antigens associated with multiple myeloma in southern Africa

While the exact aetiology of myeloma is unknown, genetic factors feature among the potential risk factors. The HLA phenotypes in African blacks with myeloma (the commonest haematopoietic malignancy in this group) have not been characterized. The purpose of this study was to determine the HLA class I and class II phenotypes of patients with multiple myeloma and to compare the findings to an ethnically matched control group of 100 individuals. Analysis of the HLA class I and class II phenotypes in 62 myeloma patients revealed: (i) a corresponding statistically significant association with HLA B18 [odds ratio (OR) 6.3; 95% confidence interval (CI) 1.013-39.727; P < 0.005]; (ii) no statistically significant association with HLA B13, Cw2, Cw6 or the DR and DQ antigens; and (iii) a statistically significant negative (protective) association with HLA Cw7 (OR 0.4; 95% CI 0.21-0.87; P < 0.005). This study suggests that although genetic factors may play a role in the multifactorial aetiology of multiple myeloma, with the exception of HLA B18, there is no specific association between HLA types and multiple myeloma in South African blacks.

Multiple myeloma in two brothers. An immunochemical and immunogenetic familial study

When multiple myeloma was diagnosed within 6 months in two brothers a family study was carried out in 34 relatives to assess the genetic factors involved. The monoclonal immunoglobulin isotype identified was identical for the two brothers (IgG kappa) as well as their genotype (a = A2B12BfSDR4 GIo2/d:A9B27BfSDR2GIol). Blood protein electrophoresis and the major histocompatibility complex markers (HLA A, B, DR, Bf, glyoxalase phenotypes) were also determined in the other family members. The immunochemical study revealed no other case of monoclonal gammapathy, but 12 cases of low gamma-globulin and three cases of polyclonal hypergammapathy were found. The immunogenetic study showed that no other family member had the a/d genotype of the two brothers, whereas nine family members were semi-identical for haplotype a and five for haplotype d. It is unlikely that a double immunochemical and immunogenetic identity in two siblings with multiple myeloma would be due only to random encounter, rather this finding suggests that, besides environmental factors, genetic factors may be involved in the pathogenesis. Systematic immunochemical and immunogenetic studies in familial multiple myeloma are proposed as a method to further elucidate an eventual genetic background in multiple myeloma.

Genetic studies in multiple myeloma. 1. Association with HLA-Cw5

Human leukocyte antigens (HLA) were identified in 22 black Americans with multiple myeloma. No significant association was observed between antigens at either the A or the B locus. At the C locus, in contrast, HLA-Cw5 was more prevalent in the patient group, four of 22 having it, compared with the control group, in which two of 138 individuals possessed it. All four patients with HLA-Cw5 were males. Those results suggest that genetic factors, perhaps in conjunction with an environmental change, may be responsible for the recent increase in incidence in myeloma in black Americans, especially in males.

HLA-DR and monoclonal gammopathy

The frequencies of the HLA-DR antigens were compared in 3 groups: a group of 33 patients with multiple myeloma (MM) or Morbus Waldenström (MW): a group of 34 persons with benign monoclonal gammopathy (BMG); and a group of 118 healthy controls. No statistically significant associations were observed.

An inherited restriction in the idiotypic variability as a possible explanation of a genetic predisposition for a monoclonal component

Genetic factors have been proposed to play a role in the aetiology of a monoclonal proliferation of B lymphocytes. As an additional genetic factor we postulate that a restriction in the idiotypic variability of an individual contributes to a genetic predisposition to monoclonal gammopathy. To support our hypothesis, we have examined three families with multiple occurrence of M-components for sharing of idiotypic antigenicity between the related M-components and between the M-components and the sera of unaffected relatives. Idiotypic antisera against five isolated M-components were raised in guinea-pigs and used in a radiobinding inhibition assay. In none of the three families was idiotypic cross-reactivity observed between the familial M-components. However, in a family with three members with an M-component, sera of first-degree relatives showed a higher inhibitory capacity than sera of non-related individuals when an idiotypic antiserum, raised against the M-component of proposita, was employed. Within this particular family the observed restriction in the idiotypic variability could have contributed to the multiple occurrence of M-components.

HLA antigens and monoclonal gammapathy

Despite the strict criteria required to distinguish Multiple Myeloma (M.M.) or Waldström's Macroglobulinemia (W.M.) from Benign Monoclonal Gammapathy (B.M.G.), nosological frontiers are still unclear and accordingly justify a comparative serological study of M.M., W.M., and B.M.G. patients.