Masked hypodiploidy: Hypodiploid acute lymphoblastic leukemia (ALL) mimicking hyperdiploid ALL in children: A report from the Children's Oncology Group.

Hyperdiploidy with greater than 50 chromosomes is usually associated with favorable prognosis in pediatric acute lymphoblastic leukemia (ALL), whereas hypodiploidy with ≤43 chromosomes is associated with extremely poor prognosis. Sometimes, hypodiploidy is "masked" and patients do not have a karyotypically visible clone with ≤43 chromosomes. Instead, their abnormal karyotypes contain 50-78 or more chromosomes from doubling of previously hypodiploid cells.

Karyotypic abnormalities associated with Epstein-Barr virus status in classical Hodgkin lymphoma.

Classical Hodgkin lymphoma (CHL) is morphologically characterized by scattered malignant Hodgkin/Reed-Sternberg (HRS) cells that are far outnumbered by surrounding reactive hematolymphoid cells. Approximately half of all cases of CHL are associated with infection by Epstein-Barr virus (EBV), an oncogenic herpesvirus that expresses a number of proteins thought to contribute to transformation. While a small number of published studies have attempted to identify recurrent cytogenetic abnormalities in CHL, no large case series have explored karyotypic differences between EBV-positive and EBV-negative tumors.

Section E6.1-6.4 of the ACMG technical standards and guidelines: chromosome studies of neoplastic blood and bone marrow-acquired chromosomal abnormalities.

These American College of Medical Genetics and Genomics standards and guidelines are developed primarily as an educational resource for clinical laboratory geneticists to help them provide quality clinical laboratory genetic services. Adherence to these standards and guidelines is voluntary and does not necessarily ensure a successful medical outcome. These standards and guidelines should not be considered inclusive of all proper procedures and tests or exclusive of other procedures and tests that are reasonably directed to obtaining the same results.

RUNX1 Amplification Increases the Risk for Thrombosis in Children With B-cell Acute Lymphoblastic Leukemia.

Background: RUNX1 (AML1) amplification in patients with B-cell acute lymphoblastic leukemia (B-ALL) has been associated with poor survival for unclear reasons. Our anecdotal experience suggests that children with B-ALL and RUNX1 amplification might be predisposed to thrombosis.

Procedure: We performed a retrospective cohort study of children with B-ALL treated from 2008 to 2014 at the North Carolina Children's Hospital.

Clonal karyotypic abnormalities associated with reactive lymphoid hyperplasia.

Cytogenetic abnormalities are important in the diagnosis and prognosis of hematolymphoid neoplasms. Although many recurrent karyotypic abnormalities are well-defined and known to underlie pathophysiologic processes contributing to malignancy, the significance of other cytogenetic changes is less clear. This uncertainty reflects an incomplete understanding of the frequency with which karyotypic abnormalities arise in benign processes.

New recurrent balanced translocations in acute myeloid leukemia and myelodysplastic syndromes: cancer and leukemia group B 8461.

Acquired chromosome abnormalities in patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are among the most valuable determinants of diagnosis and prognosis. In search of new recurrent balanced translocations, we reviewed the Cancer and Leukemia Group B (CALGB) cytogenetics database containing pretreatment and relapse karyotypes of 4,701 adults with AML and 565 with MDS who were treated on CALGB trials. We identified all cases with balanced structural rearrangements occurring as a sole abnormality or in addition to one other abnormality, excluded abnormalities known to be recurrent, and then reviewed the literature to determine whether any of what we considered unique, previously unknown abnormalities had been reported.

Mucoepidermoid carcinoma of the parotid as a secondary malignancy after chemotherapy in a child with neuroblastoma.

Secondary neoplasms are not reported frequently after neuroblastoma, which until recently was a cancer with limited long-term survival. Although salivary gland tumors in children and adolescents may be idiopathic, they are seen more often after head and neck radiation. We report a child with stage 4 neuroblastoma treated with high-dose multiagent chemotherapy without radiation therapy to his neck who, within 1 year of treatment, developed a low-grade but large and locally aggressive mucoepidermoid carcinoma of his parotid gland further characterized by a t(11;19)(q21;p13.

Autoimmune polyendocrinopathy associated with ring chromosome 18.

Phenotypic and clinical features of individuals with ring chromosome 18 [r(18)] vary with the extent of deletion of the short (18p-) or long arm (18q-). Most patients with r(18), therefore, demonstrate a clinical spectrum of both 18p- and 18q- deletions. Short stature, microcephaly, mental and motor retardation, craniofacial dysmorphism and extremity abnormalities are the most commonly reported features in patients with r(18).

Osteolipoma: radiological, pathological, and cytogenetic analysis of three cases.

Osteolipoma is a rare variant of lipoma consisting of mature adipose tissue and mature lamellar bone. The presence of non-fatty elements may lead to a wide differential diagnosis on radiology including benign and malignant lipomatous and nonlipomatous entities. The pathological diagnosis is also confounded by the presence of heterologous differentiation.

Section E9 of the American College of Medical Genetics technical standards and guidelines: fluorescence in situ hybridization.

This updated Section E9 has been incorporated into and supersedes the previous Section E9 in Section E: Clinical Cytogenetics of the 2008 Edition (Revised 02/2007) American College of Medical Genetics Standards and Guidelines for Clinical Genetics Laboratories. This section deals specifically with the standards and guidelines applicable to fluorescence in situ hybridization analysis.

American College of Medical Genetics recommendations for the design and performance expectations for clinical genomic copy number microarrays intended for use in the postnatal setting for detection of constitutional abnormalities.

Genomic copy number microarrays have significantly increased the diagnostic yield over a karyotype for clinically significant imbalances in individuals with developmental delay, intellectual disability, multiple congenital anomalies, and autism, and they are now accepted as a first tier diagnostic test for these indications. As it is not feasible to validate microarray technology that targets the entire genome in the same manner as an assay that targets a specific gene or syndromic region, a new paradigm of validation and regulation is needed to regulate this important diagnostic technology. We suggest that these microarray platforms be evaluated and manufacturers regulated for the ability to accurately measure copy number gains or losses in DNA (analytical validation) and that the subsequent interpretation of the findings and assignment of clinical significance be determined by medical professionals with appropriate training and certification.

Section E6.5 of the ACMG technical standards and guidelines: chromosome studies for solid tumor abnormalities.

Purpose: : Cytogenetic analysis of tumor tissue detects clonal abnormalities. The information obtained from these studies is utilized for diagnosis, prognosis, and patient management.

Methods: : The Working Group of the Laboratory Quality Assurance Committee of the American College of Medical Genetics provides these Standards and Guidelines for chromosome studies for solid tumors abnormalities as a resource for clinical cytogenetic laboratories.

The genetic architecture of Down syndrome phenotypes revealed by high-resolution analysis of human segmental trisomies.

Down syndrome (DS), or trisomy 21, is a common disorder associated with several complex clinical phenotypes. Although several hypotheses have been put forward, it is unclear as to whether particular gene loci on chromosome 21 (HSA21) are sufficient to cause DS and its associated features. Here we present a high-resolution genetic map of DS phenotypes based on an analysis of 30 subjects carrying rare segmental trisomies of various regions of HSA21.

Central review of cytogenetics is necessary for cooperative group correlative and clinical studies of adult acute leukemia: the Cancer and Leukemia Group B experience.

The Cancer and Leukemia Group B has performed central review of karyotypes submitted by institutional cytogenetics laboratories from patients with acute myeloid (AML) and acute lymphoblastic (ALL) leukemia since 1986. We assessed the role of central karyotype review in maintaining accurate, high quality cytogenetic data for clinical and translational studies using two criteria: the proportion of karyotypes rejected (i.e.

Guidance for fluorescence in situ hybridization testing in hematologic disorders.

Fluorescence in situ hybridization (FISH) provides an important adjunct to conventional cytogenetics and molecular studies in the evaluation of chromosome abnormalities associated with hematologic malignancies. FISH employs DNA probes and methods that are generally not Food and Drug Administration-approved, and therefore, their use as analyte-specific reagents involves unique pre- and postanalytical requirements. We provide an overview of the technical parameters influencing a reliable FISH result and encourage laboratories to adopt specific procedures and policies in implementing metaphase and interphase FISH testing.

Cytogenetic heteromorphisms: survey results and reporting practices of giemsa-band regions that we have pondered for years.

Context: Cytogenetic heteromorphisms (normal variants) pose diagnostic dilemmas. Common Giemsa-band heteromorphisms are not described in the literature, although Giemsa-banding is the method most frequently used in cytogenetic laboratories.

Objective: To summarize the responses from more than 200 cytogeneticists concerning the definition and reporting of cytogenetic heteromorphisms, to offer these responses as a reference for use in clinical interpretations, and to provide guidance for interpretation of newly defined molecular cytogenetic heteromorphisms.

HER-2 fluorescence in situ hybridization: results from the survey program of the College of American Pathologists.

Context: Fluorescence in situ hybridization (FISH) is a common method used to determine HER-2 status in breast cancer. Limited information is available concerning reproducibility of FISH in determining HER-2 gene amplification.

Objective: To present proficiency testing results of FISH for HER-2 conducted by the Cytogenetics Resource Committee of the College of American Pathologists/American College of Medical Genetics.

A clinical report of a patient with two abnormal cell lines: 46,XX,del(21)(q22.1) and 47,XX,+3.

Mosaicism for two chromosomally abnormal cell lines in the absence of a normal cell line is exceedingly rare. We report a patient with developmental and growth delay, mild dysmorphic features, a history of hypertension and hepatoblastoma who was found to be mosaic for two chromosomally abnormal cell lines. The cell lines, one containing a terminally deleted chromosome 21, the other trisomy 3, were found in her blood.

Adult de novo acute myeloid leukemia with t(6;11)(q27;q23): results from Cancer and Leukemia Group B Study 8461 and review of the literature.

Background: Acute myeloid leukemia (AML) with t(6;11)(q27;q23) is a well established but rare entity, and few studies have reported the full clinical, hematologic, and outcome data of patients with this disease.

Methods: To characterize the features of t(6;11) AML, the authors searched the Cancer and Leukemia Group B (CALGB) cytogenetic database comprising 2667 adults with newly diagnosed, de novo AML and identified 16 patients (0.6%) with t(6;11).

Submicroscopic deletion 9(q34.3) and duplication 19(p13.3): identified by subtelomere specific FISH probes.

Submicroscopic rearrangements involving chromosome ends are responsible for the unexplained mental retardation and multiple congenital anomalies observed in a number of patients. We have studied a patient with mental retardation, significant microcephaly, alopecia universalis, and other anomalies who carries an unbalanced segregant from a cryptic reciprocal translocation involving chromosomes 9 and 19. FISH studies using subtelomere specific probes revealed a derivative chromosome 9 in which the 9q subtelomeric sequence has been replaced by 19p subtelomeric sequence.