Disease associated balanced chromosome rearrangements (DBCR): report of two new cases.

Disease associated balanced chromosome rearrangements (DBCR) causing truncation, deletion, inactivation or over-expression of specific genes are instrumental in identifying and cloning several disease genes and are estimated to be much more common than anticipated. In one survey, the minimal frequency of combined balanced de novo reciprocal translocations and inversions causing abnormal phenotype is estimated to be 0.17%, a sixfold increase compared to the general population suggesting a causative linkage between the abnormality and the observed phenotypic traits. Here, we report two new cases of apparently balanced de novo translocations resulting in developmental delay and dysmorphic features.

FISH Variants with D15Z1.

We present our experience with cross-hybridization of D15Z1, used in combination with D15S10, D15S11 or SNRPN, in 109 clinical cases referred for Angelman syndrome (AS), Prader-Willi syndrome (PWS), for autism to rule out duplication of 15q11.2, or to identify structural chromosome abnormalities thought to involve chromosome 15. Nine cases with normal karyotypes studied with at least one of these probe mixtures showed an extra signal with D15Z1 on a chromosome 14. One case showed absence of the D15Z1 signal from 15p and one case showed an extra signal with D15Z1 on both chromosome 14s. Sixteen cases from this series had structural abnormalities, which included ten cases with supernumerary markers, three of which had a D15Z1 signal on a chromosome 14. The remaining cases did not have an extra signal on chromosome 14, but included rearrangements between Y and 15, 15 and 19, and a r(15), all with breakpoints in 15p11.1 or p11.2. Of the three cases with a supernumerary marker and an extra D15Z1 signal on a chromosome 14, one was a maternally derived marker, while the variant 14 was paternal in origin. The other two markers were de novo. The high frequency of variant 14 in cases with supernumerary markers (30%) was not significant by Chi-square analysis compared to the overall frequency in 109 cases of 11.9%. The overall frequency is consistent with a previous report by Stergianou et al. (1993). We can now add that a false-negative result may occur slightly less than 1% of the time. The chance that both chromosome 14 homologs will be positive for D15Z1 is theoretically about 1 in 300. If associated with an abnormal phenotype, the possibility of uniparental disomy should be ruled out.

De novo supernumerary ring chromosome 7: first report of a non-mosaic patient and review of the literature.

The present authors report the case of a 12-year-old-boy with a de novo, non-mosaic supernumerary ring chromosome 7 associated with significant developmental delay and speech difficulty. A review of the literature identified a total of 18 cases with ring chromosomes 7 who can be classified into two groups: (1) patients with a cell line that has 47 chromosomes with a small supernumerary ring chromosome 7 resulting in partial trisomy; and (2) individuals had a cell line with a large ring chromosome replacing one of the normal chromosomes 7 resulting in partial monosomy. A comparison of clinical features in the two groups of patients showed several common features such as growth and mental retardation, and facial dysmorphism, including, ear and eye anomalies. However, patients with partial trisomy have speech difficulty as a distinguishing feature, while patients with partial monosomy have skin lesions as a cardinal feature. All the published cases of ring chromosome 7, irrespective whether they are supernumerary or normal modal number, are mosaics except for one. The present subject is the first case of a de novo, non-mosaic supernumerary ring chromosome 7.

Maternal complex chromosome rearrangement ascertained through a del (13)(q12.1q14.1) detected in her mildly affected daughter.

A maternal complex chromosome rearrangement (CCR) involving chromosomes 2, 13, and 20 was ascertained in a normal female through the diagnosis of a deletion of 13q in her daughter. The child has mild clinical features and developmental delay consistent with proximal deletions of 13q that do not extend into band q32 and a del(13)(q12q14.1) that does not involve the retinoblastoma locus by FISH. Maternal studies by GTG banding and FISH showed a complex karyotype with bands 13q12.3-->13q12.1::20p13 translocated to 2p13 and bands 2pter-->2p13::13q12.3-->13q14.1 translocated into band 20p13. This would be the first report of an interstitial deletion of 13q inherited from a parental complex chromosome rearrangement.

Duplication 8 [inv dup(8)(p12p23)] with macrocephaly.

A 10-month old female is described with inv dup(8)(p12p23) who had macrocephaly with subtle changes in facial appearance and no structural birth defects. Her findings, together with those of 37 reported cases with inv dup (8), define a syndrome that emphasizes the importance of genes on the 8p region for brain development.

Duplication of 1q in a child with down syndrome and myelodysplastic syndrome.

Cytogenetic analysis of bone marrow cells was performed on a 2-year-old African-American male with Down syndrome (DS) and myelodysplastic syndrome (MDS), specifically refractory anemia with excess blasts in transformation (RAEB-T). Chromosome analysis showed, in addition to the constitutional trisomy 21, a trisomy of chromosome 11 and a dup(1)(q23q31). This duplication of 1q is apparently a new chromosomal abnormality in a child with MDS. Partial trisomy of the long arm of chromosome 1 has been reported by several authors and appears to represent a nonrandom chromosomal anomaly in patients with MDS/acute myelogenous leukemia and DS.

Trisomy 5p. A case report and review.

Trisomy 5p is a clinically discernable syndrome with characteristic clinical features. To date more than 40 patients with trisomy for various regions of short arm of chromosome 5 have been reported. Here we report a case with complete trisomy 5p and present a review of the literature.

Ring chromosome 8 syndrome: further characterization.

We describe two de novo cases of extra r(8) confirmed by fluorescent in situ hybridization (FISH). Based on these two and eight additional cases of extra r(8) confirmed by FISH, the phenotype is better documented. One of our patients had minor facial anomalies, near-normal growth, and neurological development. She had a ring in each cell analyzed. The second had minor craniofacial anomalies and growth and mental retardation. He had a small or double-sized ring in each cell. The phenotype of these 10 cases ranges from almost normal in an adult with 10% mosaicism to variable degrees of minor anomalies, growth retardation, and mental retardation overlapping the mosaic +8 syndrome.

Two distinct forms of the 64,000 Mr protein of the cleavage stimulation factor are expressed in mouse male germ cells.

Polyadenylation in male germ cells differs from that in somatic cells. Many germ cell mRNAs do not contain the canonical AAUAAA in their 3' ends but are efficiently polyadenylated. To determine whether the 64,000 Mr protein of the cleavage stimulation factor (CstF-64) is altered in male germ cells, we examined its expression in mouse testis. In addition to the 64,000 Mr form, we found a related approximately 70,000 Mr protein that is abundant in testis, at low levels in brain, and undetectable in all other tissues examined. Expression of the approximately 70,000 Mr CstF-64 was limited to meiotic spermatocytes and postmeiotic spermatids in testis. In contrast, the 64,000 Mr form was absent from spermatocytes, suggesting that the testis-specific CstF-64 might control expression of meiosis-specific genes. To determine why the 64,000 Mr CstF-64 is not expressed in spermatocytes, we mapped its chromosomal location to the X chromosome in both mouse and human. CstF-64 may, therefore, be absent in spermatocytes because the X chromosome is inactivated during male meiosis. By extension, the testis-specific CstF-64 may be expressed from an autosomal homolog of the X chromosomal gene.

Evidence for a Turner syndrome locus or loci at Xp11.2-p22.1.

Turner syndrome is the complex human phenotype associated with complete or partial monosomy X. Principle features of Turner syndrome include short stature, ovarian failure, and a variety of other anatomic and physiological abnormalities, such as webbed neck, lymphedema, cardiovascular and renal anomalies, hypertension, and autoimmune thyroid disease. We studied 28 apparently nonmosaic subjects with partial deletions of Xp, in order to map loci responsible for various components of the Turner syndrome phenotype. Subjects were carefully evaluated for the presence or absence of Turner syndrome features, and their deletions were mapped by FISH with a panel of Xp markers. Using a statistical method to examine genotype/phenotype correlations, we mapped one or more Turner syndrome traits to a critical region in Xp11.2-p22.1. These traits included short stature, ovarian failure, high-arched palate, and autoimmune thyroid disease. The results are useful for genetic counseling of individuals with partial monosomy X. Study of additional subjects should refine the localization of Turner syndrome loci and provide a rational basis for exploration of candidate genes.

Chronic eosinophilic leukemia and hypereosinophilic syndromes. Proposal for classification, literature review, and report of a case with a unique chromosomal abnormality.

The idiopathic hypereosinophilic syndromes (HES) are rare hematologic disorders characterized by persistent eosinophilia with organ involvement that encompass a wide spectrum of clinical and hematological disease states. We propose a classification scheme to further delineate these patients, and present a case of a 45-year-old male with persistent eosinophilia, severe tissue and hematologic involvement, and trisomy 15. Although multiple cytogenetic abnormalities have been associated with hypereosinophilic syndromes, this is the first reported case where trisomy 15 is the sole chromosomal abnormality.

Characterization of paired tumor and non-tumor cell lines established from patients with breast cancer.

The goal of our study was to develop a panel of tumor cell lines along with paired non-malignant cell lines or strains collected from breast cancers, predominantly primary tumors. From a total of 189 breast tumor samples consisting of 177 primary tumors and 12 metastatic tissues, we established 21 human breast tumor cell lines that included 18 cell lines derived from primary tumors and 3 derived from metastatic lesions. Cell lines included those from patients with germline BRCA1 and FHIT gene mutations and others with possible genetic predisposition. For 19 tumor cell lines, we also established one or more corresponding non-malignant cell strains or B lymphoblastoid (BL) lines, which included 16 BL lines and 7 breast epithelial (2) or stromal (5) cell strains. The present report describes clinical, pathological and molecular information regarding the normal and tumor tissue sources along with relevant personal information and familial medical history. Analysis of the breast tumor cell lines indicated that most of the cell lines had the following features: they were derived from large tumors with or without axillary node metastases; were aneuploid and exhibited a moderate to poorly differentiated phenotype; were estrogen receptor (ER)- and progesterone receptor (PR)-negative; and overexpressed p53 and HER2/neu proteins. Of 13 patients with primary breast cancers receiving curative intent mastectomies, 7 were dead after a mean period of 10 months. Our panel of paired tumor and non-malignant cell lines should provide important new reagents for breast cancer research.

Unusual presentation of multiple myeloma with "jumping translocation" involving 1q21. A case report and review of the literature.

We describe a case of multiple myeloma with unusual manifestations consisting of cutaneous xanthomatosis, temporal arteritis, retinal vasculitis with a complex karyotype, and a "jumping translocation" involving 1q21. The literature of cytogenetic studies of multiple myeloma and of jumping translocation is reviewed.

Translocation (1;22) in refractory anemia and the prognostic significance of karyotypic abnormalities in refractory anemia.

The most common cytogenetic abnormalities associated with myelodysplastic syndromes are deletions of chromosomes 5 and 7 and trisomy 8. Reciprocal translocation is relatively uncommon in refractory anemia. We describe a case of refractory anemia associated with trisomy 8 and a derivative chromosome 22 resulting from t(1;22)(q11;q11.2). The diseases and the role of the various genes that are mapped to these breakpoints are discussed. The prognostic significance of karyotypic abnormalities in refractory anemia are reviewed.

Characterization of a breast cancer cell line derived from a germ-line BRCA1 mutation carrier.

A tumor cell line, HCC1937, was established from a primary breast carcinoma from a 24-year-old patient with a germ-line BRCA1 mutation. A corresponding B-lymphoblastoid cell line was established from the patient's peripheral blood lymphocytes. BRCA1 analysis revealed that the tumor cell line is homozygous for the BRCA1 5382insC mutation, whereas the patient's lymphocyte DNA is heterozygous for the same mutation, as are at least two other family members' lymphocyte DNA. The tumor cell line is marked by multiple additional genetic changes including a high degree of aneuploidy, an acquired mutation of TP53 with wild-type allele loss, an acquired homozygous deletion of the PTEN gene, and loss of heterozygosity at multiple loci known to be involved in the pathogenesis of breast cancer. Comparison of the primary tumor with the cell line revealed the same BRCA1 mutation and an identical pattern of allele loss at multiple loci, indicating that the cell line had maintained many of the properties of the original tumor. This breast tumor-derived cell line may provide a useful model system for the study of familial breast cancer pathogenesis and for elucidating BRCA1 function and localization.

Comparison between fluorescence in situ hybridization and classical cytogenetics in human tumors.

Cytogenetic and fluorescence in situ hybridization (FISH) studies permit analyses of structural and numerical chromosome abnormalities. We compared modal chromosome count in cancer cells by FISH and classical cytogenetics (CC). Our cytogentic studies for chromosomes 3 and 17 on 134 human solid tumor cultures ¿57 small cell lung cancer (SCLC) and 77 non small cell lung cancers (NSCLC)¿, indicated a high incidence of numerical changes in these tumors. Using centromeric probes for chromosomes 3 and 17 we compared 15 tumor and 3 lymphoblastoid cultures, both by FISH (> 100 interphase nuclei) and by CC using trypsin-Giemsa G banding (> 20 metaphases). Although some intra-tumor heterogeneity was seen by FISH, we observed a high degree of concordancy (78%) in modal count by the two techniques.

Allelotyping demonstrates common and distinct patterns of chromosomal loss in human lung cancer types.

Allelic loss is a hallmark of tumor suppressor gene (TSG) inactivation. We have allelotyped 29 paired lymphoblastoid and lung cancer cell lines derived from 11 patients with small cell (SCLC) and 18 patients with non-small cell lung carcinomas (NSCLC). Statistical analysis indicated that a threshold of 30% separated non-random allelic loss from the random genetic deletions of malignancy. We have identified non-random allelic loss at 42 of 54 (78%) specific chromosomal regions examined, with 22 regions (52%) common between the two major lung cancer histologic types. There were 3 regions (7%) with allelic loss specific for SCLC and 17 regions (41%) specific for NSCLC. Furthermore, there were significant differences in loss of heterozygosity (LOH) frequencies between NSCLC and SCLC at 13 regions on eight chromosome arms (3p, 5q, 6q, 9p, 10q, 11p, 13q, and 19p). Eight homozygous deletions were present in seven cell lines at four regions, 3p12, 3p14.2, 9p21, and 10q23-25. We have also identified novel sites of chromosomal deletions. In particular, there was frequent loss at 11p13 in SCLC and loss at 6p21.3 and 13q12.3 in NSCLC. In this study, we demonstrate that a) non-random allelic losses in lung cancer involve multiple regions; b) some losses are common to both NSCLC and SCLC subtypes, whereas others are subtype specific; c) there are genetic deletions at novel chromosomal regions; and d) several homozygous deletions have been noted. Our studies demonstrate the usefulness of continuous cell lines for detailed allelotyping, for comparing genetic abnormalities between SCLC and NSCLC, and for identifying homozygous deletions.