Cancer mortality of family members of patients with chronic lymphocytic leukemia

Familial chronic lymphocytic leukemia

The role of inherited genetic factors in the etiology of chronic lymphocytic leukemia (CLL) and other B-cell lymphoproliferative disorders is now well established. Significant familial aggregation of CLL and B-cell lymphoproliferative disorders has been demonstrated, but the mode of inheritance is unknown. Identification of genes that when mutated confer an increased risk of these diseases is of immediate clinical relevance because it may offer clues to pathogenesis and highlight possible therapeutic targets. Furthermore, identification of these genes provides a greater understanding of the mechanisms of B-cell tumorigenesis in general. This article reviews current knowledge relating to inherited susceptibility to CLL and strategies that are being used to identify disease-causing mutations.

Survival patterns among lymphoma patients with a family history of lymphoma

PURPOSE

Genetic factors are important in the etiology and pathogenesis of chronic lymphocytic leukemia (CLL), Hodgkin's lymphoma (HL), and non-Hodgkin's lymphoma (NHL). Only a few small studies have assessed clinical characteristics and prognosis for familial patients, with inconsistent findings.

METHODS

Using population-based registries from Sweden and Denmark, 7,749 patients with CLL, 7,476 patients with HL, and 25,801 patients with NHL with linkable first-degree relatives were identified. Kaplan-Meier curves were constructed to compare survival in patients with lymphoma with and without a family history of lymphoma. The risk of dying was assessed using adjusted Cox proportional hazard models.

RESULTS

We found 85 patients with CLL (1.10%), 95 patients with HL (1.28%), and 206 patients with NHL (0.80%) with a family history of any lymphoma. Five-year mortality was similar for patients with CLL (hazard ratio [HR], 1.28; 95% CI, 0.95 to 1.72), HL (HR, 0.78; 95% CI, 0.49 to 1.25), and NHL (HR, 0.91; 95% CI, 0.74 to 1.12) versus without a family history of any lymphoma. Mortality was also similar for patients with versus without a family history of the same lymphoma. T-cell/anaplastic lymphoma patients with a family history of NHL had poorer outcome 5-years after diagnosis (HR, 5.38; 95% CI, 1.65 to 17.52). Results were similar for 10 years of follow-up.

CONCLUSION

With the exception of T-cell/anaplastic lymphoma, survival patterns for patients with CLL, HL, and NHL with a family history of lymphoma were similar to those for sporadic patients, suggesting that most familial lymphomas do not have an altered clinical course. Our findings provide no evidence to modify therapeutic strategies for patients with CLL, HL, or NHL based solely on family history.

A high-density SNP genome-wide linkage search of 206 families identifies susceptibility loci for chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) and other B-cell lymphoproliferative disorders display familial aggregation. To identify a susceptibility gene for CLL, we assembled families from the major European (ICLLC) and American (GEC) consortia to conduct a genome-wide linkage analysis of 101 new CLL pedigrees using a high-density single nucleotide polymorphism (SNP) array and combined the results with data from our previously reported analysis of 105 families. Here, we report on the combined analysis of the 206 families. Multipoint linkage analyses were undertaken using both nonparametric (model-free) and parametric (model-based) methods. After the removal of high linkage disequilibrium SNPs, we obtained a maximum nonparametric linkage (NPL) score of 3.02 (P = .001) on chromosome 2q21.2. The same genomic position also yielded the highest multipoint heterogeneity LOD (HLOD) score under a common recessive model of disease susceptibility (HLOD = 3.11; P = 7.7 x 10(-5)), which was significant at the genome-wide level. In addition, 2 other chromosomal positions, 6p22.1 (corresponding to the major histocompatibility locus) and 18q21.1, displayed HLOD scores higher than 2.1 (P < .002). None of the regions coincided with areas of common chromosomal abnormalities frequently observed in CLL. These findings provide direct evidence for Mendelian predisposition to CLL and evidence for the location of disease loci.

Patterns of autoimmunity and subsequent chronic lymphocytic leukemia in Nordic countries

A population-based case-control study was conducted to evaluate risk of developing chronic lymphocytic leukemia (CLL) associated with personal and/or family history of autoimmune and related diseases. Data were obtained for all (n = 7764) patients diagnosed with CLL in Sweden and Denmark over a 40-year period and with linkable relatives, 16,658 matched control subjects, and first-degree relatives of patients (n = 17,991) and control subjects (n = 39,388). Odds ratios (ORs) were calculated to quantify risk of CLL in relation to personal/family history of 32 autoimmune and related disorders. The risk of CLL was significantly increased among subjects with a personal history of pernicious anemia (OR = 1.94; 1.18-3.18), mainly in the 0- to 1-year latency period. A significantly decreased risk of CLL was found among individuals with a personal history of chronic rheumatic heart disease (OR = 0.55; 0.33-0.93), particularly persons with a long latency (10+ years) between the 2 conditions. We found no association between personal or familial occurrence of other autoimmune or related disorders and CLL. If our results are confirmed, mechanistic studies examining how pernicious anemia might promote increased occurrence of CLL and how chronic rheumatic heart disease protects against CLL, perhaps related to long-term antibiotics use, may provide insights to the as-yet-unknown etiology of CLL.

A high-density SNP genomewide linkage scan for chronic lymphocytic leukemia-susceptibility loci

Chronic lymphocytic leukemia (CLL) and other B-cell lymphoproliferative disorders (LPDs) show clear evidence of familial aggregation, but the inherited basis is largely unknown. To identify a susceptibility gene for CLL, we conducted a genomewide linkage analysis of 115 pedigrees, using a high-density single-nucleotide polymorphism (SNP) array containing 11,560 markers. Multipoint linkage analyses were undertaken using both nonparametric (model-free) and parametric (model-based) methods. Our results confirm that the presence of high linkage disequilibrium (LD) between SNP markers can lead to inflated nonparametric linkage (NPL) and LOD scores. After the removal of high-LD SNPs, we obtained a maximum NPL of 3.14 (P=.0008) on chromosome 11p11. The same genomic position also yielded the highest multipoint heterogeneity LOD (HLOD) score under both dominant (HLOD 1.95) and recessive (HLOD 2.78) models. In addition, four other chromosomal positions (5q22-23, 6p22, 10q25, and 14q32) displayed HLOD scores >1.15 (which corresponds to a nominal P value <.01). None of the regions coincided with areas of common chromosomal abnormalities frequently observed for CLL. These findings strengthen the argument for an inherited predisposition to CLL and related B-cell LPDs.

Familial risk of lymphoproliferative tumors in families of patients with chronic lymphocytic leukemia: results from the Swedish Family-Cancer Database

The importance of genetic factors in etiology of chronic lymphocytic leukemia (CLL) is suggested by family and population studies. However, the spectrum of malignancies sharing common genetic factors with CLL and the effects of sex and age on familial risk are unknown. We used the Swedish Family-Cancer Database to test for increased familial risks of CLL and other lymphoproliferative tumors. Cancer diagnoses from 1958 to 1998 were assessed in 14 336 first-degree relatives of 5918 CLL cases and in 28 876 first-degree relatives of 11 778 controls. Cancer risks in relatives of cases were compared with those in relatives of controls using marginal survival models. Relatives of cases were at significantly increased risk for CLL (relative risk [RR] = 7.52; 95% confidence interval [CI], 3.63-15.56), for non-Hodgkin lymphoma (RR = 1.45; 95% CI, 0.98-2.16), and for Hodgkin lymphoma (RR = 2.35; 95% CI, 1.08-5.08). CLL risks were similar in parents, siblings, and offspring of cases, in male and female relatives, and were not affected by the case's age at diagnosis. Anticipation was not significant when analyzed using life table methods. We conclude that the familial component of CLL is shared with other lymphoproliferative malignances, suggesting common genetic pathways. However, because clinically diagnosed CLL is uncommon, absolute excess risk to relatives is small.

Familial B-Cell Chronic Lymphocytic Leukemia in a Population of Patients from Southern Italy

We investigated the prevalence of chronic lymphocytic leukemia (CLL) in 9650 relatives of 510 CLL patients from 5 different regions (Apulia, Basilicata, Campania, Calabria, and Sicily) of Southern Italy. Data collection included a family history questionnaire. In our series of 510 CLL patients, 53 families with 2 or more individuals who had chronic lymphoproliferative disease (CLD) or other hematological malignancies were identified. In these families, 27 cases of CLL, 10 of indolent non-Hodgkin's lymphoma, and 7 of multiple myeloma were identified in relatives of CLL probands. Twenty-two relatives developed hematological malignancies other than CLD (19, acute leukemia; 3, chronic myeloid leukemia). In this study the prevalence of CLD in relatives of 510 CLL patients was 8.6% (44/510), and the prevalence of CLL in the same series was 5.2% (27/ 510). Considering the presence of clusters of individuals with hematological malignancies, overall our series contained 4 families showing a cluster with more than 2 cases. The most frequent pattern of affected family members was represented by 39 families (39/53 [73%]) with affected siblings or cousins only. Twenty siblings had CLL. The other families showed a multigenerational pattern with an affected parent-offspring relationship in only 11 (21%) of the cases and with a combination of the first 2 categories in 3 (6%) of the families. In 8 families belonging to both the last 2 mentioned groups, the affected offspring had an earlier disease onset than their parents, suggesting anticipation. We estimated the size and examined the pattern of familial aggregation of hematological malignancies, in particular CLL/CLD, in a specific geographical area. CLL was the most frequent disease in relatives, mainly siblings, of our CLL patients. Our results may be a contribution to the characterization of the epidemiological distribution pattern of CLL.

Causation of chronic lymphocytic leukemia--insights from familial disease

In Western countries B-cell chronic lymphocytic leukemia (CLL) is the most common form of leukemia. Evidence from epidemiological studies and family studies strongly supports the notion that a subset of CLL involves inherited susceptibility. Identification of genes predisposing to CLL should be useful for diagnosis and treatment, as well as serving as a model for B-cell tumorigenesis in general. Here, we review the current status of knowledge about inherited susceptibility to CLL.

A genome scan of 18 families with chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) accounts for about 30% of all leukaemias and is most prevalent in older individuals. Significant familial aggregation has been demonstrated but the mode of inheritance is unknown. Recurrent cytogenetic abnormalities are frequently found in CLL tumour cells but no susceptibility genes have been confirmed. We have collected clinical data and biospecimens on families ascertained for having at least two living patients with CLL. The current study included DNA samples from 94 individuals (38 affected patients) in 18 families. We have carried out a genome scan using the ABI 28-panel medium density linkage mapping set (average spacing of 10 cM and average heterozygosity of 80%). Genotypes for 359 markers were scored. Multipoint limit of detection (lod) scores were calculated, assuming both dominant and recessive inheritance and allowing for increased penetrance with age and genetic heterogeneity. Non-parametric linkage scores were also calculated. Lod scores of 1.0 or greater were found on regions of chromosomes 1, 3, 6, 12, 13 and 17, but none of these loci achieved statistical significance. Four of these six regions (6q, 13q, 12 and 17p) coincide with areas where cytogenetic abnormalities are frequently observed in CLL tumour cells and are, therefore, strong candidate regions for containing germ line changes.

Genetic susceptibility to chronic lymphocytic leukemia

There is increasing evidence that a subset of chronic lymphocytic leukemia is caused by an inherited predisposition. Here we review the evidence for an inherited predisposition, the characteristics of familial cases and evidence for the involvement of specific genes.

Clinical characteristics of familial B-CLL in the National Cancer Institute Familial Registry

In an ongoing study, families with two or more living cases of B-CLL in first-degree relatives have been recruited through physician and self-referral. Since 1967, 28 kindreds with 73 cases of B-CLL have been enrolled within the National Cancer Institute (NCI) Familial B-CLL Registry. Medical, clinical, and demographic information have been obtained from private physicians, patient interview, hospital records, and death certificates. We used SEER Registry data to compare characteristics of sporadic B-CLL to familial B-CLL. The mean age at diagnosis was approximately 10 years younger among familial cases (57.9 +/- 12.1) than that observed in sporadic cases (70.1 +/- 11.9). A higher percentage of second primary tumors among familial CLL cases compared to reports in sporadic was also observed (16% vs. 8.8%). However, the transformation rate to non-Hodgkin's lymphoma does not appear to be different from that reported for sporadic cases. In conclusion, we observed some differences between familial and sporadic cases; whether any of these characteristics affect survival time or severity of disease is unknown. The study of families with multiple B-CLL cases will aid in delineating the genes and environmental factors that may play a role in the development of both forms of B-CLL.

Familial chronic lymphocytic leukaemia: a survey and review of published studies

B-cell chronic lymphocytic leukaemia (CLL) is the most common form of leukaemia. To gain insight into the role of inherited factors in the disease, we have conducted a survey of the family histories of 268 CLL patients and have reviewed published familial cases and epidemiological studies. The results of our survey and published studies strongly support the hypothesis that a subset of the disease can be ascribed to a genetic predisposition. The most likely genetic model for inherited predisposition appears to be dominantly acting genes with pleiotropic effects because in many families CLL appears to be associated with other lymphoproliferative disorders.