Macroglobulinaemia in an Icelandic family

Familial predisposition to monoclonal gammopathies: deviations in B-cell biology

Monoclonal gammopathies are associated with advancing age but a familial predisposition has been recognized for several decades. A functional phenotype, characterized by increased immunoglobulin (Ig) production after mitogen stimulation has been identified in healthy members of 4 families showing a predisposition toward IgM and IgG/IgA disorders. B cells from these hyperresponders do not show increased rates of Ig gene translocations and no aberrations were detected in an in vitro model of the germinal center reaction. Array-based comparative genome hybridization revealed deletions of Ig genes in peripheral blood B cells, as expected. In addition, random changes were detected throughout the genome, presumably reflecting off-target activation-induced cytidine deaminase (AID) activity. These random changes were significantly less prevalent in B cells from hyperresponders, indicating less exposure to the germinal center environment during maturation.

Associated malignancies in patients with Waldenström's macroglobulinemia and their kin

We examined the incidence of other malignancies in 924 Waldenström's Macroglobulinemia (WM) patients and their kin. A total of 225 (24.3%) patients had ≥1 additional malignancy, with 63% predating the WM diagnosis. The most common gender-adjusted malignancies were prostate (9.4%), breast (8.0%), non-melanoma skin (7.1%), hematologic (2.8%), melanoma (2.2%), lung (1.4%) and thyroid 1.1%). Among hematologic malignancies, all 13 cases of diffuse large B-cell lymphoma and 4 cases of acute myelogenous leukemia were diagnosed after WM, and were therapy-related. Familial WM subgroup analysis showed a higher incidence of prostate cancer (P=.046) in sporadic WM patients, while patients with familial WM had a higher incidence of lung cancer (P=.0043). An increased incidence of myeloid leukemias (P<.0001) was reported among kin of familial WM patients. These data reveal specific cancer associations with WM, and provide a basis for exploratory studies aimed at delineating a common genetic basis. Additionally, these studies suggest specific cancer clustering based on familial predisposition to WM.

Familial paraproteinemia: hyper-responsive B-cells as endophenotype

The prevalence of paraproteinemias or monoclonal gammopathies increases with age. No other major risk factors have been recognized, but significant associations have been reported with chronic antigen exposure, agricultural environment, and family history. In around 130 families reported worldwide, IgG or IgA monoclonal gammopathy of undetermined significance (MGUS) occurs with multiple myeloma (MM) whereas Waldenström's macroglobulinemia (WM) is linked to IgM MGUS. Of the 8 multi-case families described here, 5 are remarkable for including both IgG/IgA and IgM type disorders. In the remaining 3 families IgG/IgA MGUS and MM occurred with Hodgkin disease and T-cell malignancies. These different patterns of familial paraproteinemia indicate different genetic backgrounds. A previously described functional phenotype of hyper-responsive B lymphocytes fulfils criteria for being an endophenotype and may be related to raised serum IgM. Identifying an endophenotype is important to ensure correct classification of affected family members and thus enhance the power of genetic studies.

Familial monoclonal gammopathy: hyper-responsive B cells in unaffected family members

BACKGROUND

  In Iceland, eight families have been identified with multiple cases of monoclonal gammopathies (MG) and other lymphoproliferative diseases. In one of these families with several cases of monoclonal gammopathy of undetermined significance (MGUS) and Waldenströms macroglobulinemia, in vitro stimulation with poke-weed mitogen revealed hyper-responsive B cells showing increased immunoglobulin production in one-third of disease-free family members.

DESIGN AND METHODS

  In this study, the families were further traced and the list of names produced was compared with The Icelandic Cancer Registry (ICR) to find all recent cases of lymphoproliferative diseases. First-degree relatives and descendants older than 20yrs of age (n=350) were selected for screening for paraprotein. Selected family members were tested for B-cell hyper-responsiveness and the lymphocyte phenotype was analysed by flow cytometry.

RESULTS

Comparison of the total list of 4370 family members with the ICR revealed 22 new cases and screening for serum paraprotein identified nine new cases of MG, eight being first-degree relatives of known probands. Sixty cases of lymphoproliferative diseases are currently known within the eight families, five of them containing both IgG/A and IgM disorders. Twelve hyper-responders (HR) were identified in four families, eight from one family, of whom four were known already. Stimulated B cells from HR had a significantly higher proportion of CD27(+) memory/plasma cells than controls.

CONCLUSION

Identification of new affected family members by screening confirms a hereditary predisposition to B-cell proliferative diseases. Contrary to most studies, IgG/A and IgM disorders occurred together in five families. In four families, enhanced B-cell responsiveness was found in healthy subjects clustered around cases.

Multigenerational information: the example of the Icelandic Genealogy Database

The first part of the chapter describes the Icelandic Genealogical Database, how it was created, what it contains, and how it operates. In the second part, an overview of research accomplished with material from the database is given.

Serum amyloid P-component and C-reactive protein in serum of healthy Icelanders and members of an Icelandic family with macroglobulinaemia

Serum levels of amyloid P-component (SAP) and C-reactive protein (CRP) were determined in 260 asymptomatic Icelanders of both sexes and various age groups and in 60 members of a family with macroglobulinaemia. In the normal group the SAP levels were normally distributed but slightly higher than in a comparable British group. Elevated levels of SAP and CRP were found in four elderly sibs of the macroglobulinaemia family. Two of them had benign monoclonal macroglobulinaemia (BMM), one had Waldenström's macroglobulinaemia and one increased polyclonal IgA. In addition, a notable small increase (2-20 micrograms/ml) in the levels of CRP was found in 6 children and 3 grandchildren of two elderly sibs with BMM. This increase in serum CRP levels was also found in five of six family members when investigated four years later. The HLA haplotypes present in the family members, including B7, are not closely associated with the various abnormal protein changes detected in the elderly sibs of the second generation or their descendents. Likewise, the increased levels of SAP, CRP or IgM are not associated with any particularly type of the genetic protein markers of blood group systems tested.

Waldenström's macroglobulinemia

Waldenström's macroglobulinemia (WM) is a clinical syndrome with diverse prognoses, and not all patients require therapy at diagnosis. Serum beta2 microglobulin is a major prognostic determinant, and asymptomatic patients with low beta2 microglobulin levels and preserved hemoglobin can be observed over long periods without therapy. Low-dose alkylating agents and purine analogs are commonly employed as initial therapy but rarely yield complete remissions. Patients who are refractory to or have relapse after alkylator or purine analogue therapy can be salvaged with purine analogs. Improvement in outcome demands a comprehensive approach aimed at increasing and sustaining complete remissions. Such an approach should probably employ Rituxan (IDEX Pharmaceuticals, La Jolla, CA) in conjunction with induction therapy, peripheral stem cell procurement before purine analog therapy, and high-dose therapy followed by maintenance therapy with interferon.

Enhanced B cell survival in familial macroglobulinaemia is associated with increased expression of Bcl-2

A family with three cases of macroglobulinaemia of undetermined significance (MGUS), and one case each of immunoblastic lymphoma, Waldentröm's macroglobulinaemia and multiple myeloma was first described 20 years ago. We have previously identified 10 out of 35 healthy family members tested whose lymphocytes produced abnormally high amounts of immunoglobulins in culture. In the present study lymphocyte subpopulations of these hyper-responders have been further characterized and lymphocyte reactivity and survival in vitro have been studied. No differences were detected in the proportions of resting B lymphocytes (CD19+) co-expressing CD5, CD10, CD11b, or CD38, and the CD4/CD8 ratio of T cells was normal before and after stimulation with pokeweed mitogen (PWM). The initial rate of response in terms of immunoglobulin production was not increased, but immunoglobulin levels continued to rise during the second week of culture whereas the production peaked at 8 days in control cultures. This was associated with significantly greater survival of lymphocytes and at 14 days surviving B cells could only be identified in samples from hyper-responders. A lymph node removed because of tuberculosis from a family member 23 years before the diagnosis of multiple myeloma showed very marked Bcl-2 expression in a B cell follicle. This was not seen in a tuberculous lymph node from an unrelated subject. Stimulated cultures from three hyper-responders tested demonstrated significantly higher retention of Bcl-2 in B cells compared with one family control and six unrelated controls. We conclude that the increased production of immunoglobulins previously observed in this family with an inherited tendency for benign and malignant B cell proliferation is the result of enhanced B cell survival, which is associated with increased expression of Bcl-2 following stimulation.

Familial macroglobulinaemia: hyperactive B-cells but normal natural killer function

An Icelandic family with two cases of benign monoclonal gammopathy and one case each of Waldenström's macroglobulinaemia, histiocytic lymphoma and multiple myeloma was first described in 1978. Nine family members had then shown raised values for se-IgM. Of these one has since died and another was not available for testing. In four of the remaining seven se-IgM had returned to normal; the three subjects who still showed raised se-IgM included the case of multiple myeloma diagnosed in 1985. Baseline production of IgM, IgG and Ig in vitro was normal in the 35 family members studied compared with 13 healthy control subjects, but the mean production of all immunoglobulin classes in response to minimal stimulation with PWM (1 microgram/ml) was significantly increased (P < 0.05). Ten family members showed markedly increased production of all three immunoglobulin classes (> 3 x SD above mean for controls). Raised production of IgM never occurred alone, indicating intact class switching. One family member showed extremely high values: IgA: 5.15 micrograms/ml, IgG: 16.3 micrograms/ml, IgM: 24.8 micrograms/ml (means for controls: 0.066, 0.123, 0.185 respectively). These 10 family members were of both sexes, ranged in age from 16 to 84 years and were clustered mainly in three distinct groups within the pedigree suggesting heredity. Proliferative responses to PWM were not significantly increased. Serum levels of interleukin-4 were tested in the patient with multiple myeloma and the family member with highest Ig production and found to be normal. We found no evidence for depressed NK function. Thus, in this family with a tendency for macroglobulinaemia and B cell derived malignancies B cell hyperreactivity was detectable by in vitro testing in several asymptomatic family members, of both sexes and all ages. No evidence was obtained for defects in regulatory mechanisms.

Familial macroglobulinemia in a Lebanese family with two sisters presenting Waldenström's disease

We report a non-consanguineous family with ten children, in which two sisters were found to have Waldenström's disease with light chain IgM monoclonal components. Immunoglobulins were examined in four siblings and revealed high serum IgM concentrations with no monoclonal component. This additional case of familial Waldenström's macroglobulinemia stresses the usefulness of screening family members of patients with monoclonal gammopathy since they may be at high risk of developing the disease.

The saga of cystatin C gene mutation causing amyloid angiopathy and brain hemorrhage--clinical genetics in Iceland

Firstly, we review investigations of hereditary cystatin C amyloid angiopathy, which is caused by a mutation in the cystatin C gene. Symptoms of brain haemorrhages, which lead to death in young adults, are the hallmark of this disorder. The mutation can now be detected by the RFLP method using Alu I restriction enzyme and cystatin C cDNA probe. Secondly, we give an overview of other clinical genetic studies in Iceland with emphasis on activities initiated or sponsored by the Genetical Committee of the University of Iceland. The list of references covers most publications on genetic studies of Icelanders.

Four brothers with Waldenstrom's macroglobulinemia

An exceptional family including four brothers with Waldenstrom's macroglobulinemia was studied. The four patients had different light chain IgM monoclonal components: two of the kappa type and two of the lambda type. Anti-idiotypic rabbit antisera, prepared for each monoclonal component, revealed no cross-reactivity. The four brothers did not share a common HLA A B DR haplotype and a genetic linkage to the HLA complex cannot be ascertained. Five of the 12 relatives had high serum immunoglobulin concentration (four IgG, three IgA, and two IgM) without monoclonal components. Two relatives showed auto-antibodies at low titer. Some of the youngest relatives exhibited immunological abnormalities and they may be high-risk subjects with regard to Waldenstrom's macroglobulinemia.

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.