Rearrangements involving 12p12 in two cases of cardiac myxoma

Familial recurrent atrial myxoma: Carney's complex

We report on a family of 4 members, all of whom have had multifocal, recurrent atrial myxomas associated with skin pigmentation, melanotic schwannomas, mucocutaneous myxomas, and tumors of the ovary and pituitary, adrenal, and thyroid glands. Immunochemistry of the myxoma cells is positive for calretinin, confirming their neuroendocrine origin. Genetic studies confirmed mutations in the gene coding protein kinase A, regulatory subunit 1-α (PRKAR1α). This is Carney's complex, characterized by multiple, mucocutaneous myxomas; pigmented lesions over the lips, conjunctiva, and genitalia; adenomas of the breast and thyroid; schwannomas; and endocrinal abnormalities including Cushing syndrome and acromegaly. Members of the family require vigorous screening, including urinary free cortisol, plasma transforming growth factor-β(1) and thyrotropin-releasing hormone, testicular ultrasound, routine echocardiographic screening, searches for cardiac and mucocutaneous myxomas in multiple locations, and genetic studies for the PRKAR1α gene sequence.

Cardiac myxoma: a cytogenetic study of two cases

Two cases of cardiac myxoma, each arising in the left atrium, are presented. One tumor contained the clonal abnormality i(17)(q10),der(20)t(1;20)(q21;q11.2) and the second tumor contained add (9)(p22),+12. Such rearrangements have not been previously reported in these tumors.

Anticipated diagnosis of left atrial myxoma following histological investigation of limb embolectomy specimens: a report of two cases

Nonfamilial myxoma occurs as a random event. The tumor is rare and can mimic other diseases. Cardiac myxomas should always be considered as a source of embolization, which need meticulous investigation and prompt indication of surgical resection. Tumors with a villous surface are prone to embolize. We report two cases of cardiac myxoma presenting as acute ischemia of one or two limbs due to embolic phenomena. The patients were females aged 55 and 37 years. Histological study of emboli taken from obstructed limb arteries in the two patients showed a picture indicating systemic embolization of a cardiac myxoma. The embolic tissue fragments showed the gross characteristics (i.e. villous surface) of the cardiac tumor. Further echocardiography and surgical removal confirmed the cardiac myxoma. Immunohistochemical study of embolectomy material disclosed strong reactivity of the tumor cells for calretinin. The histological examination of the embolectomy material can anticipate the cardiac lesion and its gross features. Calretinin is a useful marker in the differential diagnosis of cardiac myxoma with a myxoid thrombus. The necessity of histological examination of the embolectomy material is stressed.

No cytogenetic evidence for involvement of gene(s) at 2p16 in sporadic cardiac myxomas:

Cardiac myxomas are significant causes of cardiovascular morbidity and mortality. Their genetic background is presently unknown. Recently, linkage analysis in cardiac myxomas of Carney complex patients has indicated that 2p16 and 17q2 might carry genes responsible for the development of hereditary cardiac myxomas. Less is known about sporadic cardiac myxomas. To date, cytogenetic analysis has been performed on 13 sporadic cases, and no specific rearrangement has been deduced. We studied 15 sporadic cardiac myxomas and reviewed the literature. Ten of the present cases revealed abnormal karyotypes with clonal and nonclonal rearrangements including dicentric chromosomes and telomeric associations. No cytogenetic evidence was found for a role of 2p16 in the development of sporadic cases. Region 17q2 was involved in structural rearrangements, but to a lesser extent than other regions. Structural rearrangements involving regions 12p1 and 17p1 are more frequently present and might therefore harbor genes important for the development of sporadic cardiac myxomas.

Ten years of the cytogenetics of soft tissue tumors

Recent cytogenetic and molecular genetic investigations in solid tumors in general, and in soft tissue tumors in particular, have provided us with a wealth of information. We have gained new insights in how tumors may arise, and some soft tissue tumors besides their identification by pathology now also have a genetic identity. This genetic identity is defined by: specific chromosome changes and by molecular changes related to the chromosome anomalies. However, much work remains to be done. In soft tissues as in other solid tumors many tumor types await the first or more extensive chromosome investigation, and in those in which nonrandom, especially simple chromosome changes emerge, molecular studies are to be undertaken starting from the breakpoints. Those tumors that seem to deviate chromosomally or molecularly from the expected, because of already established genetic changes, must be more thoroughly investigated by both pathologists and geneticists. The same accounts for the molecular investigation of chromosomally normal tumors known to show subtypes with specific chromosomal changes: e.g. lipoma, leiomyoma.

cDNA cloning, genomic structure, and chromosome mapping of the human epithelial membrane protein CL-20 gene (EMP1), a member of the PMP22 family

CL-20 is a novel gene encoding a protein that is structurally related to but distinct from the peripheral myelin protein PMP22. Like PMP22, CL-20 is likely to play important roles in the regulation of cell proliferation, differentiation, and cell death. In this study, we describe the cloning and sequencing of a cDNA encoding the human homologue of CL-20 and characterize the genomic structure of this gene. The hCL-20 gene (HGMW-approved symbol EMP1) encodes a protein of 157 amino acids that exhibits 76% identity to the rabbit CL-20 and to the rat EMP-1, which have been described recently, and 39% identity to human PMP22. CL-20 contains four hydrophobic domains, suggesting that it is an integral membrane protein. In particular the second hydrophobic domain encoded within the fourth exon is highly conserved among CL-20, EMP-1, and PMP22, suggesting a functional role for this region. CL-20 mRNA is abundant in squamous-differentiated bronchial epithelial cells; however, low levels of CL-20 mRNA can be detected in several human tissues by Northern analysis. Retinoic acid, which inhibits squamous differentiation, represses CL-20 expression in normal human bronchial epithelial cells. The genomic structure of the hCL-20 gene was analyzed using a P1 vector containing this gene. The hCL-20 gene contains five exons about 0.2, 0.12, 0.1, 0.14, and 2.2 kb and four introns about 15, 1.9, 0.1, and 0.7 kb. We have mapped the hCL-20 gene to chromosome 12p12 by fluorescence in situ hybridization.