Detection of monoclonal IGH rearrangements in circulating cells from healthy first-degree relatives of patients with multiple myeloma.

Multiple myeloma (MM) is characterized by abnormal proliferation of clonal plasma cells or monoclonal plasmacytosis, resulting in accumulation of clonal immunoglobulins. Monoclonal gammopathy of unknown significance (MGUS) is considered a premorbid stage for developing MM. Studies have shown an increased risk of MGUS in first-degree relatives of patients with MM. Detection of immunoglobulin heavy chain gene (IGH) rearrangement provides a useful tool for assessing clonality. The aim of this study was to determine clonality in peripheral blood samples from 61 healthy first-degree relatives of MM probands by sorting circulating lymphocytes and detection of the IGH rearrangements in these cells. We detected 16 out of 61 (26.2%) relatives with monoclonal complete and incomplete IGH rearrangements; only three of them showed elevated monoclonal immunoglobulin in the serum protein electrophoresis. We conclude that this strategy is able to identify efficiently clonality in peripheral blood samples from first-degree relatives of patients with MM, who have a non-negligible risk of developing MGUS or other plasma cell dyscrasias.

47,XXX/45,X/46,XX mosaicism in a patient with Turner phenotype and spontaneous puberal development.

OBJECTIVE: To describe a patient with infertility and phenotypic combination of Turner and triple-X syndrome related to mos 47,XXX/45X/46,XX karyotype. DESIGN: Case report. SETTING: División de Genética, Centro de Investigación Biomédica de Occidente and Hospital de Ginecología y Obstetricia, CMNO, Instituto Mexicano del Seguro Social. PATIENT(S): The 24-year-old patient presented a phenotypic combination of Turner syndrome and X polysomy. She showed wide and short neck, low posterior hairline, cubitus valgus, bilateral shortening of the fourth and fifth metacarpals, multiple nevi, and müllerian anomalies but had spontaneous pubarche, thelarche, and menarche. INTERVENTION(S): Laboratory evaluations, imaging studies, ovarian biopsy, G-banding karyotype, and in situ fluorescence hybridization. MAIN OUTCOME MEASURE(S): Clinical and laboratory findings. RESULT(S): A karyotype: mos 47,XXX/45X/46,XX was found in the cytogenetic studies, a bicornuate uterus in the ultrasonographic scan, and a normal ovarian profile in the laboratory tests. CONCLUSION(S): The infertility in the present case can be related to either bicornuate uterus or subclinical abortions due to aneuploid ova. Cytogenetic assessment provides important information regarding infertile patients with uterine factors and short stature.

Detection of clonal immunoglobulin and T-cell receptor gene recombination in hematological malignancies: monitoring minimal residual disease.

A considerable number of studies on hematological malignancies have recently demonstrated that the identification of rearrangements in immunoglobulin (Ig) and T-cell receptor (TCR) genes are important tools for diagnosis and follow-up of B- and T-cell disorders. The heterogeneity of these malignancies makes it difficult to carry out a precise assessment in all patients despite well-established morphological and immunophenotyping criteria. Clonal analysis of hematological malignancies is supported by the fact that all malignant cells have a common clonal origin with identically rearranged Ig and/or TCR genes. Identification of B- or T-cell clonality in polyclonal tissue such as the blood is indicative of a lymphoproliferative process. Germline gene segments of Ig heavy chain (IGH), Ig kappa (IGK), Ig lambda (IGL) and TCR are rearranged in each lymphocyte during B- and T-cell differentiation. A specific combination of gene segments and somatic mutations occurring during this process is responsible for the wide diversity of antigen-specific receptors and antibodies. Ig and TCR rearrangements are considered the "fingerprint" of each lymphocyte and therefore can be used as tumor-specific PCR targets for detection of residual malignant cells present after treatment. Determination of minimal residual disease (MRD) has a proven prognostic value and enables effective early interventional treatment. This is becoming routinely implemented in several treatment protocols and is increasingly used in guidelines for drug therapy and stem cell transplantation. In this review we focus on: (1) the process of gene rearrangements in B- and T-cells, (2) principles of polymerase chain reaction (PCR)-based assays and real-time PCR methods commonly used to detect and follow clonal Ig and TCR rearrangements, (3) multiplex primer sets recently designed by the BIOMED-2 concerted action group, and (4) application of these techniques in MRD detection.

Clinical and genetic heterogeneity in patients with mosaic variegated aneuploidy: delineation of clinical subtypes.

Mosaic variegated aneuploidy (MVA) is a rare autosomal recessive syndrome related to BUB1B gene mutations and characterized by multiple mosaic aneuploidies, cancer predisposition, and a distinct phenotype. We report on two mildly affected sibs with MVA syndrome but without BUB1B mutation. Both patients exhibited growth retardation, frontal bossing, triangular face and micrognathia but not microcephaly or cancer. Aneuploidies were assessed both in G-banded metaphases from lymphocyte cultures and in interphase nuclei from buccal cells by FISH. Screening of 23 exons and intron-exon boundaries of BUB1B was also carried out. These patients were then compared with other 19 MVA patients screened for BUB1B mutations. Around one half of the cultured lymphocytes from our patients had aneuploidies ranging from nullisomies to heptasomies; the most frequent abnormalities were trisomies (42%) and monosomies (28%). FISH results demonstrated more chromosomal losses than gains. Screening of BUB1B in our two patients failed to identify any mutation. A review of the 21/35 patients screened for BUB1B demonstrated three clinical pictures. Patients with monoallelic BUB1B mutations were severely affected with Dandy-Walker complex (7/8), cataracts (6/6), and Wilms' tumor (7/8); premature chromatid separation (PCS) was observed in 8/8 propositi and 7/7 carrier parents. Patients without BUB1B mutations were mildly affected with no evidence of cancer, Dandy-Walker malformation or cataract, and rarely (1/7) showed PCS. Finally, patients with biallelic BUB1B mutations showed a moderate phenotype. The distinct MVA clinical groups delineated here point to involvement of at least another mitotic spindle checkpoint gene in addition to the BUB1B gene.