Hereditary chronic lymphocytic leukemia: an extended family study and literature review

High-throughput sequencing for biology and medicine

Advances in genome sequencing have progressed at a rapid pace, with increased throughput accompanied by plunging costs. But these advances go far beyond faster and cheaper. High-throughput sequencing technologies are now routinely being applied to a wide range of important topics in biology and medicine, often allowing researchers to address important biological questions that were not possible before. In this review, we discuss these innovative new approaches-including ever finer analyses of transcriptome dynamics, genome structure and genomic variation-and provide an overview of the new insights into complex biological systems catalyzed by these technologies. We also assess the impact of genotyping, genome sequencing and personal omics profiling on medical applications, including diagnosis and disease monitoring. Finally, we review recent developments in single-cell sequencing, and conclude with a discussion of possible future advances and obstacles for sequencing in biology and health.

Anticipation in families with chronic lymphocytic leukemia and other lymphoproliferative disorders

Fifty-one parent-offspring pairs with chronic lymphocytic leukemia (CLL) or other lymphoproliferative disorders (nonCLL) such as malignant lymphoma, multiple myeloma, or other types of lymphocytic leukemia than CLL were ascertained independently in 38 families. There were 30 CLL-CLL parent-offspring pairs and 21 pairs with nonCLL in parents and/or in offspring. The median age of onset of disease was 13 years lower in the offspring than in the parents when comparing all 51 pairs (P < 0.001). This difference was mainly caused by a significantly lower age at onset in offspring with parental nonCLL (P < 0.001) where paternal disease was transferred especially to sons, while affected offspring to parents with CLL have the same age at debut of disease than their parents (P = 0.130) and a nearly equal transfer to sons and daughters. The low-malignant follicular small B-cell lymphoma was the predominant diagnosis within nonCLL. Anticipation is pointed out as one likely mechanism behind the lower age at onset of disease in offspring than in parents, even if a part of this difference is ascribed to a generally earlier diagnosis with modern technology in offspring than in parents.

Genetic predisposition to human disease: allele-specific expression and low-penetrance regulatory loci

The two alleles of a gene can be expressed at different levels, the extreme example being imprinting, a condition in which one allele is totally suppressed. Recently, subtle differences in the expression of the two alleles have been detected in numerous human genes and in a few cases, have been associated with a genetic predisposition to disease. The underlying mechanisms are largely unexplored.

Genetic counseling for DAPK1 mutation in a chronic lymphocytic leukemia family

Genetic counseling has become the clinical bedrock of hereditary cancer management. Countless advances in molecular genetics contributing to the identification of cancer-causing germline mutations have increased its importance. We report a unique genetic counseling experience involving a family with hereditary chronic lymphocytic leukemia and the cancer-causing mutation in the death-associated protein kinase 1 gene (DAPK1). This hereditary disorder currently lacks any preventive or curative interventions for mutation carriers. This family has been under our investigation for a decade, during which time genealogy, cancer of all anatomic sites, medical and pathology records, and, whenever possible, slides and tissue blocks were reviewed. Family attendance at three group-oriented family information service sessions provided intensive education about this disease. Blood and skin fibroblasts were obtained for molecular genetic studies of DNA leading to the discovery of the DAPK1 mutation in the family. Their intellectual and emotional reaction to its presence or absence in them was assessed. This family serves as a model for genetic counseling in disorders for which lifesaving intervention is not yet possible.

Molecular profiling of chronic lymphocytic leukaemia: genetics meets epigenetics to identify predisposing genes

Molecular profiling may lead to a better understanding of a disease. This knowledge is especially important in malignancies, where multiple alterations are required during the progression from premalignant to malignant stages. Such information can be useful for the development of novel biomarkers that allow the prediction of a clinical course, response to treatment or early detection. Molecular data is also utilized to develop targeted therapies. Moreover, gene defects identified in profiling studies will help to understand the molecular pathways disrupted in the disease. This review provides an overview of molecular profiling approaches in chronic lymphocytic leukaemia (CLL). We will describe our current understanding of genetic alterations in CLL, the use of familial CLL for the identification of predisposing mutations, and the search for epigenetic alterations in CLL.

Downregulation of death-associated protein kinase 1 (DAPK1) in chronic lymphocytic leukemia

The heritability of B cell chronic lymphocytic leukemia (CLL) is relatively high; however, no predisposing mutation has been convincingly identified. We show that loss or reduced expression of death-associated protein kinase 1 (DAPK1) underlies cases of heritable predisposition to CLL and the majority of sporadic CLL. Epigenetic silencing of DAPK1 by promoter methylation occurs in almost all sporadic CLL cases. Furthermore, we defined a disease haplotype, which segregates with the CLL phenotype in a large family. DAPK1 expression of the CLL allele is downregulated by 75% in germline cells due to increased HOXB7 binding. In the blood cells from affected family members, promoter methylation results in additional loss of DAPK1 expression. Thus, reduced expression of DAPK1 can result from germline predisposition, as well as epigenetic or somatic events causing or contributing to the CLL phenotype.

Chromosomal aberrations and CD38 expression in two siblings with B-cell chronic lymphocytic leukemia: a report of two siblings

In this study our purpose was to define chromosomal aberrations and CD38 expression in male siblings 69 and 66-years-old with B-cell chronic lymphocytic leukemia (B-CLL). Cells from peripheral blood were analysed by comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). The alteration detectable by CGH was the over-representation of the Y chromosome in both samples. Interphase FISH were performed using locus (13q14 and 17p53) and centromere (chromosome 12, 17 and Y) specific DNA probes. One brother (patient 1, 69 years of age) showed deletion of the 13q14 region, this alteration was associated with low CD38 expression, both predicting a favourable prognosis. However, the younger patient's (patient 2, 66 years of age) cells expressed CD38 in high percent, which is considered as an indicator of poor prognosis, and deletion of the 13q14 was not seen. Other, relatively frequent chromosomal alterations including trisomy 12 and deletion of 17p53 were not present in any of the samples. The cytogenetic findings and the CD38 expression are in concordance with the clinico-pathological data of the siblings. Thus, we found the variability of these parameters described in B-CLL even in the familial form of the disease.