Application of multicolor banding for identification of complex chromosome 18 rearrangements

Multicolor chromosome banding (mBAND) is a recently developed technique that allows the delineation of chromosomal regions with a resolution of a few megabase pairs. The resolution of mBAND is slightly below that of conventional chromosome banding; however, the color bands have a great value in identifying chromosomal abnormalities, particularly complex chromosome rearrangements, and intrachromosome exchanges (ie, inversions, deletions, duplications, and insertions). These abnormalities cannot be defined easily by conventional cytogenetic analysis or chromosome paint. In this report, we present the application of the mBAND analysis for identification of complex intrachromosome rearrangements of chromosome 18 in a child with dysmorphic features.

Persistent gestational trophoblastic disease after an androgenetic/biparental fetal chimera: a case report and review

We present a case of a dichorionic/diamniotic twin pregnancy in which one twin presented with ultrasound findings suggestive of molar changes in the placenta. The placenta of twin A seemed to be grossly enlarged and cystic, and twin A was small for gestation. After an inevitable abortion, a detailed histological and genetic evaluation was performed on the fetus and placenta from twin A, including traditional cytogenetic techniques, microsatellite marker analysis, fluorescent in situ hybridization, and p57 immunostaining. It was determined that twin A was a chimera with a biparental XX cell line and an androgenetic XY cell line. The 2 cell lines were present in both the placenta and the fetus. The patient later developed and was treated for persistent gestational trophoblastic disease, which has been shown to have an increased risk after an androgenetic conception. Cases of mosaicism or chimerism involving an androgenetic cell line may be difficult to diagnose histologically but are critical to identify because of the increased risk for persistent gestational trophoblastic disease. Therefore, we emphasize the importance of using multiple molecular, cytogenetic, and immunohistochemical techniques when diagnosing cases involving such unusual placental abnormalities. To our knowledge, this is the first reported case of persistent gestational disease after a fetal chimera.

Identification and characterization of novel human transcripts embedded within HMGA2 in t(12;14)(q15;q24.1) uterine leiomyoma

The high mobility group A2 protein (HMGA2) has been implicated in the pathogenesis of mesenchymal tumors such as leiomyoma, lipoma and hamartoma. HMGA2 was pinpointed by mapping the breakpoints in the chromosomal translocations in 12q15, especially the t(12;14) that is commonly seen in uterine leiomyoma. It is generally assumed that altered expression of HMGA2 is an early event in the pathway to tumor formation. Here, we show evidence that three novel transcripts, A15, B6 and D12 are located within the HMGA2 gene itself and are transcribed from the opposite strand. These embedded transcripts are expressed at 6-20-fold higher levels in tumors compared to matched myometrium from the same patients. We estimate that the domain of increased expression extends 500kb on chromosome 12q15, and encompasses the majority of t(12;14) translocation breakpoints. However, a corresponding domain of consistently altered expression is not seen on chromosome 14 or outside of the chromosome 12 multiple aberration region. These data suggest that t(12;14) breakpoints contribute to the pathogenesis of uterine leiomyoma by interrupting a complex regulation of HMGA2 and other genes embedded within and around it. We also discovered a novel laminin receptor gene, transcribed from the opposite strand, within the promoter region of HMGA2. Although the roles for these embedded transcripts are still unknown, preliminary data suggest that they are members of the family of non-coding RNA and that they may play an important role in the pathology of uterine leiomyoma.

A locus for renal malformations including vesico-ureteric reflux on chromosome 13q33-34

Congenital anomalies of kidney and urinary tract (CAKUT), including vesico-ureteric reflux (VUR), are major causes of ESRD in childhood. Herein is reported evidence for a locus on 13q33q34 associated with CAKUT. Deletion mapping of chromosome 13q was performed in four children with CAKUT using 31 microsatellite markers on peripheral blood genomic DNA that was obtained from the patients and their parents. mRNA expression of the positional candidate genes was compared with sequences in electronic databases in silico and also studied in adult and fetal mouse kidneys using reverse transcription-PCR. The children (three girls; age range 5 to 17 yr) had varying severity of developmental delay and other organ system involvement. The spectrum of CAKUT included high-grade VUR (n = 2), renal dysplasia (n = 2), and hydronephrosis (n = 1). Both the children with VUR had evidence of renal failure with one of them developing ESRD. Deletion mapping identified a 7-Mb critical region flanked by markers D13S1311 and D13S285. There are 33 genes (12 known; 21 computer predicted) in this region. In silico expression studies showed matches for 14 of these genes in the kidneys and 10 in the bladder expressed sequenced tags databases. Mouse kidney studies showed that of the 24 genes examined, several had variable expression through the different stages of renal development, whereas five of the genes were not expressed at all. Herein is reported a new locus on chromosome 13q33q34 that can be associated with VUR with several genes showing mRNA expression patterns that suggest their potential for involvement in renal/urinary tract developmental anomalies.

Variable outcomes in mosaic trisomy 16: five case reports and literature analysis

OBJECTIVES

To report five cases of mosaic trisomy 16 with variable outcomes in the context of the literature on mosaic trisomy 16. Complications in these cases include preeclampsia, IUGR, fetal anomalies, and death, with no predictable pattern.

METHODS

Observation of five new cases and statistical analysis of 125 reported cases of mosaic trisomy 16 with prenatal detection and outcome data.

RESULTS

(1) IUGR, premature delivery, and/or physical anomalies are observed commonly, even when the trisomy is thought to be confined to the placenta; (2) Level II mosaicism for trisomy 16 in amniotic fluid may reflect a true mosaic state with phenotypic consequences; (3) FISH is more sensitive than traditional cytogenetics in detecting mosaicism in all tissue types examined; (4) hCG levels can be extremely elevated, and MS-AFP levels are often elevated; and (5) Uniparental disomy (UPD) increases the rates of IUGR and physical anomalies in CPM cases.

CONCLUSION

While there is no obvious mosaic trisomy 16 syndrome, IUGR and heart defects commonly occur, even if the mosaicism appears to be confined to the placenta. A completely normal outcome occurs only in about 20% of the cases; however, complications can often be limited to prematurity, small-for-gestational-age infants, and/or minor or surgically reparable birth defects.

Tetrasomy 9q in an infant with cleft palate and multiple anomalies

We report a patient with partial tetrasomy 9q resulting from a de novo triplication of 9q13q22.1. The clinical features, including microcephaly, beaked nose, short palpebral fissures, camptodactyly, joint contractures, and moderate developmental delay were similar to trisomy 9q, although our patient also had unique features including cleft palate and several unexplained fractures. The latter could be secondary to abnormal tone and contractures. Although tetrasomy 9p is a well-known entity, our patient, to our knowledge, is the first and only individual reported to have tetrasomy 9q.

Loss of DNA copy number of 10q is associated with aggressive behavior of leiomyosarcomas: a comparative genomic hybridization study

Leiomyosarcomas (LMS) account for 10-20% of all soft tissue sarcomas. We analyzed 10 primary, 5 metastatic, and 2 recurrent extrauterine LMS. Genomic imbalances were detected in 15 out of the 17 tumors. The most common regions of loss were 13q (59%, 10 of 17), 10q (59%, 10 of 17), 2q (35%, 6 of 17), and 16q (29%, 5 of 17). The most common region of gain was 5p (35%, 6 of 17). High-level gain of DNA copy number was detected in 6p and 17p. Loss of function of tumor suppressor genes or the activation of oncogenes (or both of these factors) resulting from these copy number changes might play an important role in the development of extrauterine LMS. Large tumors and tumors with metastasis showed 10q deletions. Gain of 5p was detected only in G3 tumors. These findings are consistent with our earlier study on uterine LMS and indicate that loss of 10q and gain of 5p are associated with an aggressive behavior of LMS. A larger series of cases is needed to confirm these results.

Tetrasomy 9q in an infant with cleft palate and multiple anomalies

We report a patient with partial tetrasomy 9q resulting from a de novo triplication of 9q13q22.1. The clinical features, including microcephaly, beaked nose, short palpebral fissures, camptodactyly, joint contractures, and moderate developmental delay were similar to trisomy 9q, although our patient also had unique features including cleft palate and several unexplained fractures. The latter could be secondary to abnormal tone and contractures. Although tetrasomy 9p is a well-known entity, our patient, to our knowledge, is the first and only individual reported to have tetrasomy 9q.

Twin pregnancy with a chimeric androgenetic and biparental placenta in one twin displaying placental mesenchymal dysplasia phenotype

OBJECTIVES

The aim was to report an unusual trizygotic pregnancy that resulted in live-born twins. The placenta of one twin had placental mesenchymal dysplasia (PMD), which resulted from a chimeric fusion of an androgenetic zygote and a normal biparental zygote. The literature review was summarized.

METHODS

The case was first detected by prenatal ultrasound, and was then followed by a histologic and detailed genetic investigation. The literature on PMD, complete hydatidiform moles (CHMs), and placental mosaicism and chimerism was also reviewed.

RESULTS

One placenta of a twin pregnancy was noted to be diffusely cystic and enlarged. The macroscopic and microscopic findings were consistent with the diagnosis of PMD; however, genetic findings confirmed confined placental chimerism involving a normal biparental 46,XY male conceptus and an androgenetic 46,XX complete hydatidiform mole.

CONCLUSIONS

This case represents a rare placental abnormality, PMD, which may have a diverse etiology. Therefore, detailed histologic and genetic analysis were performed for an accurate diagnosis.

A case of myelodysplastic syndrome with acquired monosomy 7 in a child with a constitutional t(1;19) and a mosaicism for trisomy 21

A 3-year-old patient presented with anemia, thrombocytopenia, and blasts in the peripheral blood. A bone marrow aspirate revealed a myelodysplastic syndrome (MDS). A mosaic abnormal female karyotype 46,XX, t(1;19)(q42; p13.1)c[12]/ 47,idem,+21c[3]/ 47,idem,-7,+21c,+mar[7] was obtained on G-banded metaphases from unstimulated bone marrow aspirate cell culture. To rule out constitutional abnormalities, we performed a cytogenetic analysis on the patient's phytohemagglutinin-stimulated peripheral blood and cultured skin fibroblasts. A karyotype of 46,XX,t(1;19) (q42;p13.1)c was found in all 20 peripheral lymphocytes analyzed, confirming the constitutional origin of the translocation. In addition, 5 out of 50 cells from two separate cultures of the skin fibroblasts contained an extra chromosome 21. The presence of two cell lines in multiple cultures indicates that the patient is a true low-level mosaic for trisomy 21. Because of the finding of monosomy 7 and a marker chromosome only in the trisomy 21 clone, we conclude that the leukemic clone arose from a hematopoietic precursor with constitutional trisomy 21. It is also possible that the t(1;19) played some role in the development of the MDS. Because acute myelogenous leukemia (AML) and MDS with Down syndrome (DS) have distinct biologic and clinical features, the identification of DS patients with a mild or normal phenotype in the AML/MDS population is of fundamental importance for clinical diagnosis and management.

Clinicopathologic, Immunophenotypic, and Molecular Cytogenetic Fluorescence In Situ Hybridization Analysis of Primary and Secondary Cutaneous Follicular Lymphomas

Although primary cutaneous follicular lymphoma (FL) is considered a distinct variant of FL in the World Health Organization classification ("cutaneous follicle center lymphoma"), its biologic relationship to nodal FL remains controversial. The clinical, morphologic, immunophenotypic, and molecular cytogenetic features of 17 patients with primary cutaneous FL were studied and compared with 16 patients with secondary cutaneous FL. The head and neck region was the most frequent site at initial skin presentation in both the primary and secondary cases. Among the primary cases, 29% of the 31 biopsies were grade 1, 48% grade 2, 13% grade 3, and 10% grade 3 with diffuse large B-cell (DLBCL) areas. Among the secondary cases, 38% of the 29 skin biopsies were grade 1, 45% grade 2, 3% grade 3, and 7% grade 3 with DLBCL areas with two not evaluable. A floral-like pattern was observed in 32% of primary FL but only 5% of secondary cases. Histologic progression was found in 21% of patients. CD10 expression was demonstrated in 90% (27 of 30) of primary cases and 96% (22 of 23) of secondary cases. Bcl-6 was expressed in all cases tested. Bcl-2 expression was detected in 57% (17 of 30) of the primary cases (100% of grade 1, 43% of grade 2, 40% of grade 3), whereas all secondary cases were bcl-2 positive (P=0.0002). The t(14;18) translocation was identified by interphase fluorescence in situ hybridization (FISH) in biopsies from 31% (4 of 13) of the patients with primary FL compared with 77% (10 of 13) of those with secondary lymphoma (P <0.05). Seven of the 17 (41%) patients with primary disease had cutaneous relapse, including 1 who also developed nodal disease. Bcl-2 positivity was seen in 4 of these 7 patients. Eight of the 16 (50%) patients with secondary FL had cutaneous relapse. Primary and secondary cutaneous FL share many clinical and phenotypic features, but primary cases may have some distinctive morphologic features, more frequently lack bcl-2 protein, and often lack the t(14;18) translocation. These findings suggest that primary cutaneous FL are distinctive and often but not always have a pathogenesis different from most of nodal and secondary cutaneous FL.

The clinical use of karyotyping spontaneous abortions

OBJECTIVE

The objective of this study was to assess the clinical use of routinely karyotyping spontaneous abortion material.

STUDY DESIGN

We retrospectively reviewed the records of the Pittsburgh Cytogenetics Laboratory from January 1, 1998, to December 31, 2001, for all tissues from spontaneous losses at 20 weeks' gestation or less for which complete medical records were available.

RESULTS

There were 517 submitted samples of which 28 (5.4%) failed to grow in culture. Overall, 55.8% of samples were abnormal; 52.3% of normal results were male. In samples from pregnancies at 13 weeks or less the rate of abnormality was 69.1%. When analyzed by maternal age, the rate of abnormality for first-trimester losses was 57.2% in women younger than 35 years, and 82.3% in those 35 years or older. There was no difference in the rate of abnormality when comparing first loss with two or more losses, first pregnancy with two or more pregnancies, or the presence or absence of at least one live birth.

CONCLUSION

Chromosome abnormalities are the cause for pregnancy loss in 50% to 80% of cases, depending on maternal age and gestational age at time of the loss. Karyotyping of spontaneous losses in the first trimester beginning with the patient's second loss provides clinically important etiologic information and decreases the number of evaluations necessary for recurrent pregnancy loss.

Large-scale genotyping of complex DNA

Genetic studies aimed at understanding the molecular basis of complex human phenotypes require the genotyping of many thousands of single-nucleotide polymorphisms (SNPs) across large numbers of individuals. Public efforts have so far identified over two million common human SNPs; however, the scoring of these SNPs is labor-intensive and requires a substantial amount of automation. Here we describe a simple but effective approach, termed whole-genome sampling analysis (WGSA), for genotyping thousands of SNPs simultaneously in a complex DNA sample without locus-specific primers or automation. Our method amplifies highly reproducible fractions of the genome across multiple DNA samples and calls genotypes at >99% accuracy. We rapidly genotyped 14,548 SNPs in three different human populations and identified a subset of them with significant allele frequency differences between groups. We also determined the ancestral allele for 8,386 SNPs by genotyping chimpanzee and gorilla DNA. WGSA is highly scaleable and enables the creation of ultrahigh density SNP maps for use in genetic studies.

Steroid-resistant nephrotic syndrome and congenital anomalies of kidneys: evidence of locus on chromosome 13q

BACKGROUND

Steroid-resistant nephrotic syndrome (SRNS) and congenital anomalies of kidney and urinary tract (CAKUT) are major causes of renal dysfunction in children. Although a few patients with 13q deletion have been previously reported with renal anomalies, the association of SRNS with 13q has not been reported and critical regions associated with CAKUT have not been identified. We present the results of deletion mapping studies to identify the critical regions.

METHODS

Cytogenetic and deletion mapping studies were performed on DNA obtained from peripheral blood of two children with renal anomalies and interstitial deletion of 13q as well as their parents. Twenty eight microsatellite markers with a spacing of 1-8 Mb (1-3 cM) were utilized.

RESULTS

The patients (both males, 5 and 10 years old) had varying severity of developmental delay and other neurologic disorders. The renal involvement included hydronephrosis, ureterocele, renal dysplasia, and mesangioproliferative SRNS. Our studies imply existence of at least two critical regions in the 13q area that are linked to CAKUT. The first is a 7 Mb region defined by markers D13S776 and D13S891 shared by both patients. The second is a much larger region extending at least 33 Mb above D13S776 seen in one patient with severe renal malformations and SRNS.

CONCLUSION

We report an association of chromosome 13q with CAKUT as well as SRNS. Our studies suggest the presence of more than one gene in this region that is likely to be involved in renal development and function.

Comparative study of primary and recurrent ovarian serous carcinomas: comparative genomic hybridization analysis with a potential application for prognosis

OBJECTIVES

The purpose of this study is to comparatively characterize genomic imbalances in primary and recurrent ovarian serous carcinomas and to identify genomic alterations that may be used as a marker for prognosis.

METHODS

Twenty ovarian serous carcinomas were studied by comparative genomic hybridization (CGH).

RESULTS

Genomic alterations were found in all of the tumors. The most common regions involving gain of DNA copy numbers are 1q41q44, 8q22q24, 19p12q13.1, 20q12q13, 3q26q29, 12p12p13, 2p22p25, 7p14p21, 5p15.2p15.3, and 17q22q25. The most common regions with loss of DNA copy numbers are Xp11.2q13, 4q31q35, Xp21p22.3, 18q22q23, 13q22q31, 9p22p24, and 16q22q24. High-level gains were detected at chromosomal regions of 1q41q44, 2p22p25, 3q26q29, and 19p12q13.1. Comparative analysis of primary and recurrent tumors showed that gains of 2p22p25, 19p12q13.1, and 20q12q13 and loss of 5q14q22 were more common in the recurrent high-grade tumors. About 85% of the tumors showed increases in DNA copy numbers in the regions (2p and 8q) harboring the myc family gene. Patients with tumor containing fewer than seven chromosomal aberrations showed longer survival time.

CONCLUSION

The myc oncogene family may play a role in the pathogenesis of ovarian serous carcinomas. Our study suggests that tumors with gains of 2p22p25, 19p12q13.1, and 20q12q13 and loss of 5q14q22 may be at high risk for recurrence. Furthermore, the patients' survival time inversely correlates with the numbers of chromosomal alterations found in their tumors. CGH analysis may have a clinical application in predicting prognosis and risk of recurrence in patients with ovarian serous carcinomas.

Primary and secondary cutaneous diffuse large B-cell lymphomas: a multiparameter analysis of 25 cases including fluorescence in situ hybridization for t(14;18) translocation

Although primary cutaneous diffuse large B-cell lymphomas (DLBCLs) except for those of the leg are grouped together with primary cutaneous follicle center cell lymphoma in the European Organization for Research and Treatment of Cancer classification of primary cutaneous lymphomas, they typically lack the usual phenotypic profile of follicular lymphoma. Whether they are truly of follicular center cell origin, have a molecular pathogenesis similar to nodal follicular lymphoma, or have any biologic features that distinguish them from secondary DLBCL involving skin remains uncertain. To address these issues, a retrospective multiparameter study of 25 patients including clinical, histologic, immunophenotypic, and cytogenetic analyses was performed. A classic CD10+, bcl-6+ follicular center cell profile was found in 10 (40%) cutaneous DLBCL (2 of 11 primary, 5 of 8 secondary, 3 of 6 unclassified) with bcl-2 expression seen only in the nonprimary cases. Of the remaining cases, 14 cases (56%) were CD10-, bcl-6+, bcl-2+/- (9 primary) and one case (4%) was CD10-, bcl-6-, bcl-2+ (0 primary). Fluorescence in situ hybridization analysis showed a t(14;18) in 0 of 9 primary and 3 of 5 secondary cases. Primary cases were frequently found in the head/neck region, whereas secondary cases were more common on the trunk and extremities. Patients with primary disease were all alive, usually having received only local therapy, at a median follow-up of 19 months. Most secondary cases were treated with chemotherapy with only one untreated patient dead of disease at a median follow-up of 5 months. Primary cutaneous DLBCLs therefore appear to be distinctive as they have fewer features of follicular lymphoma than do secondary cases. Nevertheless, some appear to be of follicular center cell origin, even though they probably have a different molecular pathogenesis than most nodal follicular lymphomas.

Three cases of tetrasomy 9p

We report three cases of tetrasomy 9p, two of which were confirmed prenatally. All three had characteristic findings on ultrasound and at birth. We also present a review of the literature, which suggests that a recognizable phenotype for this condition is emerging. Common findings on prenatal ultrasound include intrauterine growth restriction, ventriculomegaly, cleft lip or palate, and renal anomalies. These findings can provide a clue toward the prenatal diagnosis of this condition. There is also a clearly recognizable phenotype at birth. Facial characteristics include hypertelorism, broad nasal bridge/bulbous or beaked nose, cleft lip/palate, ear anomalies, and micrognathia. The exact extent of the isochromosome does not seem to predict severity, but mosaic cases are less severe, or at least have a greater probability of survival.

Tetrasomy 15q25.3 --> qter resulting from an analphoid supernumerary marker chromosome in a patient with multiple anomalies and bilateral Wilms tumors

We describe a girl who had been followed since birth for apparent Shprintzen-Goldberg syndrome (SGS), with macrosomia, long fingers and toes, and craniosynostosis, and presented at 4 years of age with bilateral Wilms tumors (also called nephroblastoma). Cytogenetic analysis of her peripheral blood revealed a de novo supernumerary marker chromosome. This stable marker chromosome is present in 19 of 20 lymphocytes analyzed, as well as in all 40 tumor cells (20 from each tumor) studied. Classical and molecular cytogenetic studies indicate that the marker is derived from an inverted duplication of chromosome 15q25.3 --> qter and contains a neocentromere. The presence of this marker chromosome in our patient results in tetrasomy 15q25.3 --> qter. The relationship between her genotype and phenotype are discussed in light of genes, including IGF1R and FES, mapped to the aneusomic segment.

Genomic imbalances in ovarian borderline serous and mucinous tumors

We analyzed 25 ovarian borderline tumors (13 serous and 12 mucinous tumors) by comparative genomic hybridization (CGH). Genomic imbalance was detected in 85% of serous tumors and 75% of mucinous tumors. Different patterns of genomic alterations were identified in serous and mucinous tumors. Gain of the X chromosome was common in both serous (30%) and mucinous (42%) tumors. However, gain of chromosome 8 was detected exclusively in 38% of serous and mixed sero-mucinous tumors, but not in any pure mucinous tumors. According to the present and previous studies, gain of chromosome 8 is the most common abnormality in borderline serous tumors. Gain of the same chromosome is also common in high grade and advanced stage serous carcinomas, but uncommon in early stage serous carcinomas. In addition gain of chromosome X is common in borderline serous and mucinous tumors, while loss of chromosome X is predominant in invasive carcinomas. These findings do not support the multi-step progression theory from borderline tumor to high-grade, advanced stage carcinoma, but indicate that the borderline ovarian tumor is a distinct entity. Genes in chromosome 8 may be critical for the development and the differentiation of borderline serous tumors.

Paternal origins of complete hydatidiform moles proven by whole genome single-nucleotide polymorphism haplotyping

Complete hydatidiform moles (CHMs) are diploid tumors that result from fertilization of an empty ovum by a haploid 23,X sperm. In most cases, the resulting duplication of the genome gives rise to a 46,XX genotype and is thought to be androgenetic in origin. If this hypothesis is correct, then the genotypes of all polymorphic markers in CHMs should be homozygous. We used a dense set of single-nucleotide polymorphism (SNP) markers, evenly spaced throughout the genome, to definitively test this hypothesis. We genotyped genomic DNA samples from five CHMs and their corresponding maternal samples with 1494 SNP markers using high-density microarrays (HuSNP). As predicted, the maternal samples were heterozygous at >25% of the markers, which is consistent with the expected average heterozygosity of this panel of SNPs. In contrast, the five CHM samples were heterozygous at <0.75% of the SNP markers, which shows that these diploid tumors consist of a duplicated set of chromosomes. Because the CHM genotypes represent the haplotypes of their genomes, our results show that long-range haplotypes can be obtained easily with this resource and that a collection of such samples is a simple way to obtain reference haplotypes for association studies in various populations.

Genomic alterations in uterine leiomyosarcomas: potential markers for clinical diagnosis and prognosis

Genomic alterations were analyzed in 21 uterine leiomyosarcomas (ULMSs) by comparative genomic hybridization. DNA copy number changes were detected in all 21 tumors. The most frequent losses were 13q (16/21 = 76%), 10q (13/21 = 62%), 16q (8/21 = 38%), 12p (7/21 = 33%), and 2p (9/21 = 43%). The most common gains were 17p (8/21 = 38%), Xp (7/21 = 33%), and 1q (7/21 = 33%). High-copy-number gains (ratio > 1.5) were identified in Xp, 1q, and 17p. Loss of 13q was identified in both low-grade and high-grade tumors. Inactivation of a tumor suppressor gene in 13q may be an early event in the development of leiomyosarcomas. Loss of 10q, 2p, and 12p and gains of 1q as well as 17p were frequently found in high-grade tumors and recurrent tumors. Inactivation of tumor suppressor genes and activation of oncogenes in these regions may be associated with a more aggressive behavior of ULMS. Patients with only loss of 13q and without the other alterations listed above had longer survival times. Gains of Xp, 17p, and 1q and losses of 13q, 10q, 16q, 12p, and 2p have been reported in extra-uterine leiomyosarcomas. Our findings indicate that the pathogenesis of uterine leiomyosarcomas and extra-uterine leiomyosarcomas follows the same genetic pathways.

Parental origin and phenotype of triploidy in spontaneous abortions: predominance of diandry and association with the partial hydatidiform mole

The origin of human triploidy is controversial. Early cytogenetic studies found the majority of cases to be paternal in origin; however, recent molecular analyses have challenged these findings, suggesting that digynic triploidy is the most common source of triploidy. To resolve this dispute, we examined 91 cases of human triploid spontaneous abortions to (1) determine the mechanism of origin of the additional haploid set, and (2) assess the effect of origin on the phenotype of the conceptus. Our results indicate that the majority of cases were diandric in origin because of dispermy, whereas the maternally-derived cases mainly originated through errors in meiosis II. Furthermore, our results indicate a complex relationship between phenotype and parental origin: paternally-derived cases predominate among "typical" spontaneous abortions, whereas maternally-derived cases are associated with either early embryonic demise or with relatively late demise involving a well-formed fetus. As the cytogenetic studies relied on analyses of the former type of material and the molecular studies on the latter sources, the discrepancies between the data sets are explained by differences in ascertainment. In studies correlating the origin of the extra haploid set with histological phenotype, we observed an association between paternal-but not maternal-triploidy and the development of partial hydatidiform moles. However, only a proportion of paternally derived cases developed a partial molar phenotype, indicating that the mere presence of two paternal genomes is not sufficient for molar development.

Is there an interchromosomal effect in reciprocal translocation carriers? Sperm FISH studies

Chromosome translocations have been known to affect disjunction of chromosomes unrelated to the translocation in the mouse and in Drosophila. However, in humans, an interchromosomal effect in chromosome translocations has not been demonstrated. The availability of techniques that allow the study of nondisjunction in sperm cells has permitted us to evaluate the possibility of an interchromosomal effect in male translocation heterozygotes. In this study, multicolor fluorescence in situ hybridization was used to determine levels of disomy for the clinically relevant chromosomes X, Y, 13, 18, and 21 in 332,858 spermatozoa from nine reciprocal translocation heterozygotes and nine controls with normal karyotypes. The specific translocations studied were as follows: t(10;12)(p26.1;p13.3), t(2;18)(p21;q11.2), t(3;19)(p25;q12), t(5;8)(q33;q13), t(11;22)(q23;q11), t(3;4)(p25;p16), t(8;9) (q24.2;q32), t(10;18)(q24.1;p11.2), and t(4;10)(q33;p12.2). Comparisons of disomy rates between carriers and controls were performed by using the Mann-Whitney test. Our results showed that the rates of sex chromosome hyperhaploidy were similar in controls (0.21%) and in translocation carriers (0.19%). Similarly, the frequencies of disomy for chromosomes 13, 18, and 21 did not differ significantly between controls and carriers (0.05% versus 0.08%, 0.07% versus 0.03%, and 0.14% versus 0.20%, respectively). Sex chromosome nondisjunction was more common than nondisjunction of chromosomes 13 and 18 both in controls (P=0.0057) and in carriers (P=0.0008). Similarly, the rates of chromosome disomy for chromosome 21 were higher than those for chromosomes 13 and 18 in both controls (P=0.0031) and translocation carriers (P=0.0057). In our study, the excess of chromosome 21 disomy versus disomy of the other autosomes was more pronounced in carriers than in controls. Thus, although the difference of disomy 21 between controls and carriers was not statistically significant, it is worthy of attention.

Genomic and functional map of the chromosome 14 t(12;14) breakpoint cluster region in uterine leiomyoma

A translocation involving chromosomes 12 and 14 [t(12;14)(q15;24.1)] is commonly seen in benign smooth muscle tumor as uterine leiomyoma (UL). A contig of P1-derived artificial chromosome and bacterial artificial chromosome clones on chromosome 14, encompassing a t(12;14) breakpoint cluster region (BCR) in UL, was generated principally using the recently developed HAPPY map of chromosome 14 as a framework (P. H. Dear et al., 1998, Genomics 48: 232-241). Three UL t(12;14) breakpoints have been localized within this contig, showing that a BCR of at least 400 kb exists on chromosome 14. Other studies of tumors with t(12;14) rearrangements similarly show breakpoints within a 475-kb multiple aberration region on chromosome 12. Thus t(12;14) is an example of a translocation in which the breakpoints are located within a BCR on both chromosome 12 and chromosome 14, justifying the identification of expressed sequences that are altered in these BCR regions. A total of four expressed sequences were identified in the BCR on chromosome 14. Two of these were novel cDNAs (D14S1460E and D14S1461E). The chromosome 14 cDNAs were expressed in multiple adult tissues. The identification of a large breakpoint cluster region on chromosome 14 suggests that translocations in this region mediate their effects at a distance and also that elements that predispose this region to recurrent chromosomal translocation may be widely distributed.

Nongestational choriocarcinoma in the postpartum period: a case report

PURPOSE

To determine the tissue of origin (gestational versus nongestational) of an extensive metastatic choriocarcinoma in an 18-year-old woman to determine prognosis and treatment.

METHODS

DNA microsatellite polymorphisms after polymerase chain reaction (PCR) amplification of the tumor tissue and blood from the patient, husband, and daughter were used to determine the tissue of origin.

RESULTS

Molecular analyses revealed that the tumor shared the genetic features of only the patient. She responded well to multiagent chemotherapy.

CONCLUSIONS

Molecular analysis is a useful tool to determine whether a choriocarcinoma occurring in a female patient of child-bearing age is gestational or nongestational when clinical findings are not clearly indicative of the primary.

Molecular analysis of chromosome 7q21.3 in uterine leiomyoma: analysis using markers with linkage to insulin resistance

Recent sibling-pair linkage analyses have indicated possible linkage of noninsulin dependent diabetes mellitus (NIDDM) with a number of markers on the long arm of chromosome 7. A coincidental and recent discovery is that specific genetic anomalies identified on chromosome 7 in uterine leiomyoma tumor cells in many cases correspond, cytogenetically, to the same region where genetic linkage to insulin resistance has been identified. In the present study, 15 closely spaced microsatellite markers were used to finely map deletion breakpoints and to test for allelic loss of 7q markers in 12 uterine leiomyoma tumor samples with cytogenetically defined deletions. Of the 9 informative tumor samples, three exhibited breakpoints in the same region where genetic linkage to insulin resistance has been identified (between PON and UT901). Because breakpoints in neoplasias often occur within or adjacent to expressed sequences, these breakpoints may provide a molecular tool to aid in the identification of candidate genes for insulin resistance.

Apparently balanced t(1;7)(q21.3;q34) in an infant with Coffin-Siris syndrome

Coffin-Siris syndrome is a multiple anomaly/mental retardation syndrome characterized by "coarse" facial appearance, hypoplastic or absent nails on the fifth digits, generalized hirsutism with sparse scalp hair, hypotonia, and developmental delay. Due to several reports of affected sibs with or without a mildly affected parent, both autosomal recessive and autosomal dominant inheritance have been suggested. All previous patients with well-documented Coffin-Siris syndrome are chromosomally normal, and the gene has not been mapped. We report on an infant with typical findings of Coffin-Siris syndrome who also has a de novo apparently balanced translocation of chromosomes 1 and 7, karyotype 46,XY,t(1;7)(q21.3;q34). The parental chromosomes are normal and none of the relatives have signs of Coffin-Siris syndrome. The breakpoints 1q21.3 and 7q34 are suggested as possible locations for a Coffin-Siris gene.

Familial skewed X inactivation: a molecular trait associated with high spontaneous-abortion rate maps to Xq28

We report a family ascertained for molecular diagnosis of muscular dystrophy in a young girl, in which preferential activation (> or = 95% of cells) of the paternal X chromosome was seen in both the proband and her mother. To determine the molecular basis for skewed X inactivation, we studied X-inactivation patterns in peripheral blood and/or oral mucosal cells from 50 members of this family and from a cohort of normal females. We found excellent concordance between X-inactivation patterns in blood and oral mucosal cell nuclei in all females. Of the 50 female pedigree members studied, 16 showed preferential use (> or = 95% cells) of the paternal X chromosome; none of 62 randomly selected females showed similarly skewed X inactivation was maternally inherited in this family. A linkage study using the molecular trait of skewed X inactivation as the scored phenotype localized this trait to Xq28 (DXS1108; maximum LOD score [Zmax] = 4.34, recombination fraction [theta] = 0). Both genotyping of additional markers and FISH of a YAC probe in Xq28 showed a deletion spanning from intron 22 of the factor VIII gene to DXS115-3. This deletion completely cosegregated with the trait (Zmax = 6.92, theta = 0). Comparison of clinical findings between affected and unaffected females in the 50-member pedigree showed a statistically significant increase in spontaneous-abortion rate in the females carrying the trait (P < .02). To our knowledge, this is the first gene-mapping study of abnormalities of X-inactivation patterns and is the first association of a specific locus for recurrent spontaneous abortion in a cytogenetically normal family. The involvement of this locus in cell lethality, cell-growth disadvantage, developmental abnormalities, or the X-inactivation process is discussed.

Two discrete regions of deletion at 7q in uterine leiomyomas

This study further defines the region of consistent deletion of chromosome 7 in uterine leiomyomas. We have examined 74 leiomyomas for allelic loss of markers spanning the 7q22 region defined by markers D7S518 and D7S471. Forty tumors with cytogenetically defined 7q deletions, twenty-nine tumors without cytogenetically visible 7q deletions, and five tumors with no cytogenetic information were examined for allelic loss of D7S518, D7S666, D7S515, D7S658, D7S496, D7S692, and D7S471. Loss of heterozygosity for one or more of these loci was observed in twenty-eight leiomyomas with cytogenetically defined 7q deletions and in three leiomyomas with a normal karyotype. Allelic loss of D7S666 was common and was observed in all twenty-three informative tumors with 7q deletions and in two tumors with normal karyotypes. This study indicates the presence of a tumor suppressor gene in close proximity to the D7S666 locus. Eight tumors followed an unusual pattern of allelic loss. These tumors showed retention of heterozygosity for at least one locus flanked by deleted loci. These results suggest the possibility that two discrete regions of deletion at 7q22 are involved in the development of a subset of leiomyomas.

The use of interphase FISH for prenatal diagnosis of Pallister-Killian syndrome

Pallister-Killian syndrome (tetrasomy 12p) is a relatively rare aneuploidy syndrome characterized by the presence of mosaicism for an isochromosome 12p [i(12p)]. We report two new cases diagnosed following chorionic villus sampling and an abnormal ultrasound, respectively. Fluorescent in situ hybridization (FISH) was used to enumerate the number of interphase cells containing the isochromosome. The results of these studies illustrate the importance of the use of interphase FISH to detect the presence of the i(12p) in uncultured, non-dividing cells. A review of the literature identified 23 additional cases of Pallister-Killian syndrome diagnosed prenatally. Approximately 50 per cent of these cases were associated with the presence of a congenital diaphragmatic hernia. We suggest that a perinatal-lethal form of Pallister-Killian syndrome is underdiagnosed and recommend that all cases of prenatally detected diaphragmatic hernia be tested for Pallister-Killian syndrome using interphase FISH on uncultured amniocytes.

Identification of mosaicism in Prader-Willi syndrome using fluorescent in situ hybridization

We report on our findings of 4 patients with mosaicism for a deletion of chromosome 15, most commonly associated with Prader-Willi syndrome (PWS). We examined a series of typical and atypical PWS patients in order to identify cytogenetically undetected deletions, using fluorescence in situ hybridization. In 4 of the patients analyzed we detected a deletion in 14-60% of peripheral blood leukocytes, using four commercially available probes. Our results indicate that mosaicism may play a role in the etiology of some PWS cases. These findings may be especially useful in patients who display discrepancies between clinical phenotype and established diagnostic criteria. Methylation and microsatellite polymorphism analyses of 2 patients with low-level mosaicism failed to identify the deletion. We propose that fluorescence in situ hybridization is the most effective method for detecting somatic mosaicism, since a large number of cells can be individually examined for the presence or absence of a specific deletion.

Pitt-Rogers-Danks syndrome: the result of a 4p microdeletion

Pitt-Rogers-Danks syndrome (PRDS) is a rare, presumed autosomal recessive, syndrome with pre- and postnatal growth retardation, microcephaly, characteristic facial appearance, seizures, unusual palmar creases and developmental delay. Since the first description in 1984, only 7 cases have been reported. We report the identification of a 4p microdeletion in 2 new patients, who were previously diagnosed with PRDS, as well as the sibs in Pitt et al. [1984]. PRDS can no longer be considered autosomal recessive. Although our cases are attributable to a microdeletion in 4p16, it is uncertain if the critical region involves a single locus or multiple loci or to what extent this region overlaps with the critical region for Wolf-Hirschhorn syndrome.

Molecular cytogenetics: an essential component of modern prenatal diagnosis

Traditional cytogenetic studies with high-resolution banding techniques have been the mainstay of prenatal diagnosis for > 20 years. However, this approach is limited by the resolution of light microscopy, and it requires cultured cells, necessitating a significant delay in obtaining chromosome studies. The advent of molecular cytogenetics, or fluorescence in situ hybridization, has added an adjunctive tool to overcome both these limitations. During a 16-month period 35 prenatal diagnosis cases had molecular cytogenetic studies performed; 71% of the evaluations were informative. We present five of these cases to illustrate the benefits of this technique for clinical prenatal diagnosis.

Cytogenetic and histologic correlation of peripheral nerve sheath tumors of soft tissue

Cytogenetic analysis was performed on 11 peripheral nerve sheath tumors of soft tissue from 10 patients. They include 6 benign and 5 malignant schwannomas. Five cases which include two benign, one cellular and two malignant schwannomas had a known association with a nerve, but only one patient with malignant schwannoma has clinically documented neurofibromatosis type I. All the patients had a normal diploid constitutional karyotype. Two cases of cellular schwannoma were analyzed by routine cytogenetic analysis and fluorescence in situ hybridization (FISH). One tumor was karyotyped as 45, XX,-13,-22 +mar; and the other case had a 45,X,-Y,t(1;17) (p12;q11.2) karyotype. In the latter, the breakpoint in 17q occurred below the centromere and is at or in the region of the Neurofibromatosis Type 1 (NF1) gene. Four benign tumors had a normal diploid karyotype. One hypodiploid malignant schwannoma with myxoid features demonstrated monosomy of chromosomes 17 and 22 by FISH analysis. The rest of the malignant schwannomas showed a wide range of numerical and structural aberrations, with frequent loss of 22q and gains of chromosomes 2 and 7. Loss of a sex chromosome was observed in cellular as well as malignant schwannomas. Regional karyotypic evolution was noted in one malignant schwannoma. Cytogenetic analysis may prove to be useful in identifying tumors, such as cellular schwannomas, which, because of their histologic features may be inadvertently categorized as malignant. Simultaneous involvement of NF1 and NF2 genes, which are located on chromosomes 17q and 22q, respectively, should be investigated at a molecular level in both benign and malignant tumors of peripheral nerves.

Prenatal diagnosis of uniparental disomy 15 following trisomy 15 mosaicism

Maternal uniparental disomy 15 (UPD15), responsible for approximately 25 per cent of Prader-Willi syndrome cases, is usually caused by maternal meiosis I non-disjunction associated with advanced maternal age. These cases may initially be detected as mosaic trisomy 15 during routine prenatal diagnostic studies. In such cases, PCR (polymerase chain reaction) microsatellite analysis of uncultured cells makes prospective prenatal diagnosis for UPD15 possible with results available in 2-4 days. We have performed molecular analyses on a series of seven cases of mosaic trisomy 15 identified in amniotic fluid (AF, n = 3) or chorionic villus samples (CVS, n = 4) from patients initially referred for advanced maternal age or abnormal triple screen. In all cases, the maternal ages were > or = 35 years and maternal meiosis I non-disjunction was documented as the cause of the trisomy in all informative cases (n = 5). Of the three case with mosaic trisomy 15 at amniocentesis, two showed the presence of the trisomy in the fetus. Molecular analysis showed one case with maternal UPD15 in the euploid cell line and one case with biparental inheritance. Both of these families elected to terminate the pregnancies based on the presence of true fetal mosaicism. In the third case, low-level trisomy 15 mosaicism in the amniotic fluid was not confirmed in a follow-up amniotic fluid sample and molecular analysis indicated biparental inheritance in the fetus. For the four trisomy 15 mosaics detected at CVS, molecular analysis was performed on direct amniotic fluid cell lysates for prospective diagnosis of UPD at 14-16 weeks' gestation. Follow-up cytogenetic analysis of the amniotic fluid in all four cases was normal, indicating confined placental mosaicism. Molecular analysis showed one of these four cases to have maternal heterodisomy 15. Based on the likelihood of Prader-Willi syndrome due to maternal UPD15, the couple chose to terminate the pregnancy. The total of two of seven cases of trisomy 15 mosaicism resulting in UPD15 is consistent with the theoretical expectation of one-third and indicates a high risk of UPD in such pregnancies. Therefore, UPD testing should be offered in all cases of mosaic trisomy 15 encountered in CVS or amniocentesis.

Gene structure, DNA methylation, and imprinted expression of the human SNRPN gene

The human SNRPN (small nuclear ribonucleoprotein polypeptide N) gene is one of a gene family that encode proteins involved in pre-mRNA splicing and maps to the smallest deletion region involved in the Prader-Willi syndrome (PWS) within chromosome 15q11-q13. Paternal only expression of SNRPN has previously been demonstrated by use of cell lines from PWS patients (maternal allele only) and Angelman syndrome (AS) patients (paternal allele only). We have characterized two previously unidentified 5' exons of the SNRPN gene and demonstrate that exons -1 and 0 are included in the full-length transcript. This gene is expressed in a wide range of somatic tissues and at high, approximately equal levels in all regions of the brain. Both the first exon of SNRPN (exon -1) and the putative transcription start site are embedded within a CpG island. This CpG island is extensively methylated on the repressed maternal allele and is unmethylated on the expressed paternal allele, in a wide range of fetal and adult somatic cells. This provides a quick and highly reliable diagnostic assay for PWS and AS, which is based on DNA-methylation analysis that has been tested on > 100 patients in a variety of tissues. Conversely, several CpG sites approximately 22 kb downstream of the transcription start site in intron 5 are preferentially methylated on the expressed paternal allele in somatic tissues and male germ cells, whereas these same sites are unmethylated in fetal oocytes. These findings are consistent with a key role for DNA methylation in the imprinted inheritance and subsequent gene expression of the human SNRPN gene.

DNA methylation patterns in human tissues of uniparental origin using a zinc-finger gene (ZNF127) from the Angelman/Prader-Willi region

In order to further our understanding of the epigenetic modifications of DNA and its role in imprinting, we examined DNA methylation patterns of human tissues of uniparental origin. We used complete hydatidiform moles (CHM), which are totally androgenetic conceptions, to examine the paternal methylation pattern in the absence of a maternal contribution and we used ovarian teratomas to represent the maternal counterpart. We carried out an analysis of DNA methylation of a gene which has been shown to contain sites which are differentially methylated in a parent-specific fashion. The gene, ZNF127, is located on chromosome 15q11-q13 in the region associated with Prader-Willi and Angelman syndromes. The parent-of-origin DNA methylation has been postulated to reflect the presence of an imprint and recent studies have confirmed that ZNF127 is differentially expressed only from the paternal chromosome. We identified a unique pattern of hyper- and hypomethylated sites in androgenetic conceptions which was nearly identical to the paternal pattern found in sperm. This may represent the paternal germ-line methylation imprint. We also studied partial hydatidiform moles, non-molar triploid conceptions, normal chorionic villi, and somatic tissue. These all demonstrated a modified DNA methylation pattern characteristic of normal chorionic villi with only limited findings of the imprint. Our results suggest that human androgenetic conceptions may provide an excellent model to analyze epigenetic DNA modifications, such as methylation, in imprinted genes. The paternal allele-specific methylation imprint will also be useful clinically to confirm the androgenetic nature of suspected molar conceptions in which parental blood samples may not be available.

Transplantation of congenital primitive neuroectodermal tumor of fetus to the uterus of mother: application of biotin-labeled chromosome-specific probes

We report a 38-year-old gravida 3, para 3, white female with an unremarkable history and normal amniocentesis, who delivered a male infant with a large pedunculated and ulcerated tumor by vaginal delivery. A portion of the tumor was sheared and expelled with the normal placenta at the time of delivery. The biopsy of the infant mass and the expelled tissue showed histologic features of a small round cell tumor with immunohistochemical features of a primitive neuroectodermal tumor (PNET). The infant eventually died at the age of 4 weeks as a result of extensive dissemination of tumor. The mother had postpartum bleeding, and fractional dilation and curettage procedures at 6 weeks and 4 months after delivery revealed tumor similar to that of the infant. The mother underwent radical hysterectomy and bilateral salpingo-oophorectomy, which revealed a neoplasm at the junction of the lower uterine segment and cervix. Fluorescent in situ hybridization (FISH) study of both the infant's tumor and the mother's uterine tumor showed positivity for the Y chromosome by using a classical alpha-satellite Y chromosome-specific probe. These findings support the hypothesis that the tumor was transferred from the fetus to the mother.

Identification of an unbalanced cryptic translocation t(9;17)(q34.3;p13.3) in a child with dysmorphic features

We report a case of an unbalanced cryptic telomeric translocation 46,XY,der(17),t(9;17)(q34.3;p13.3) in a boy with dysmorphic features and developmental delay. The proband had intrauterine growth retardation, postnatal short stature, and mild microcephaly. Magnetic resonance imaging showed incomplete myelination, but no evidence of lissencephaly. Cytogenetic analysis of the proband's peripheral blood showed an abnormal 17p. Fluorescence in situ hybridisation (FISH) with a Miller-Dieker cosmid probe did not detect a deletion for that area. Further analysis with a 17p telomere specific probe identified an unbalanced telomeric translocation. The same probe was used to determine the presence of an apparent balanced translocation t(9;17)(q34.3;p13.3) in the mother of the proband. The balanced translocation was confirmed with two cosmids that map distally on 9q34.3. Two phenotypically normal half sibs, a maternal aunt, a maternal uncle, and the maternal grandmother were found to be balanced translocation carriers as well. A subtle translocation carriers as well. A subtle translocation is one mechanism that can produce an abnormal phenotype in a patient who had a normal karyotype at lower band resolution levels.

Molecular and cytogenetic analysis of chromosome 7 in uterine leiomyomas

Uterine leiomyomas are benign tumors that arise clonally from smooth muscle cells of the myometrium. Cytogenetic studies of uterine leiomyomas have shown that about 40% have chromosome abnormalities and that deletion of 7q is a common finding. The observations suggest the possible location of a growth-suppressor gene within the 7q21-q22 region. Molecular genetic analysis of cytogenetically normal tumors has frequently shown somatic loss of specific tumor suppressor genes detected by loss of heterozygosity in the critical region. To test the hypothesis that chromosome region 7q21-q22 contains a growth-suppressor gene involved in the development of leiomyomas, we examined 92 leiomyomas for allelic loss of 7q markers spanning the cytogenetically defined critical region. Forty tumors with cytogenetically defined 7q deletion, 45 tumors without cytogenetically visible 7q deletion, and seven tumors with no cytogenetic information were examined for allelic loss of loci D7S489, D7S440, D7S492, D7S518, D7S471, D7S466, and D7S530. Loss of heterozygosity for one or more of these loci was observed in 23 of 40 (57.5%) of the tumors with deletion of 7q and in 2 of 45 cases without a cytogenetically visible deletion. The tumors with cytogenetic deletion of 7q, but no loss of 7q21-q22 markers, were mosaics, with only a minority of cells containing the cytogenetic deletion. The critical region of loss is defined by the markers D7S518 and D7S471, each showing loss in approximately 50% of informative cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitogenic effect of basic fibroblast growth factor and estradiol on cultured human myometrial and leiomyoma cells

OBJECTIVE

We compared the mitogenic effect of basic fibroblast growth factor with and without estradiol on myometrial and leiomyometrial cells.

STUDY DESIGN

The mitogenic effect of basic fibroblast growth factor on myometrial cells was measured by thymidine incorporation and cell count. The mitogenic effect of basic fibroblast growth factor with and without estradiol as measured by thymidine incorporation was compared between myometrial and leiomyometrial cells.

RESULTS

Both human myometrial and leiomyometrial cells showed significant (p = 0.004 and p = 0.001, respectively), dose-dependent incorporation of thymidine in response to basic fibroblast growth factor. Leiomyometrial cells showed significantly (p = 0.04) less thymidine incorporation compared with matched normal myometrial cells. The addition of estradiol with basic fibroblast growth factor did not result in a further increase in thymidine incorporation.

CONCLUSIONS

Both myometrial and leiomyometrial cells respond to basic fibroblast growth factor with increased thymidine incorporation; however leiomyometrial cells are less responsive than are matched normal myometrial cells. The addition of estradiol is not synergistic with basic fibroblast growth factor.

Molecular characterization of two proximal deletion breakpoint regions in both Prader-Willi and Angelman syndrome patients

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are distinct mental retardation syndromes caused by paternal and maternal deficiencies, respectively, in chromosome 15q11-q13. Approximately 70% of these patients have a large deletion of approximately 4 Mb extending from D15S9 (ML34) through D15S12 (IR10). To further characterize the deletion breakpoints proximal to D15S9, three new polymorphic microsatellite markers were developed that showed observed heterozygosities of 60%-87%. D15S541 and D15S542 were isolated from YAC A124A3 containing the D15S18 (IR39) locus. D15S543 was isolated from a cosmid cloned from the proximal right end of YAC 254B5 containing the D15S9 (ML34) locus. Gene-centromere mapping of these markers, using a panel of ovarian teratomas of known meiotic origin, extended the genetic map of chromosome 15 by 2-3 cM toward the centromere. Analysis of the more proximal S541/S542 markers on 53 Prader-Willi and 33 Angelman deletion patients indicated two classes of patients: 44% (35/80) of the informative patients were deleted for these markers (class I), while 56% (45/80) were not deleted (class II), with no difference between PWS and AS. In contrast, D15S543 was deleted in all informative patients (13/48) or showed the presence of a single allele (in 35/48 patients), suggesting that this marker is deleted in the majority of PWS and AS cases. These results confirm the presence of two common proximal deletion breakpoint regions in both Prader-Willi and Angelman syndromes and are consistent with the same deletion mechanism being responsible for paternal and maternal deletions. One breakpoint region lies between D15S541/S542 and D15S543, with an additional breakpoint region being proximal to D15S541/S542.

Translocation (6;10)(p21;q22) in uterine leiomyomas

A translocation between chromosomes 6 and 10 was observed in two uterine leiomyomas. Translocation (6;10) may be important in the pathogenesis of a subgroup of uterine leiomyomas.

Xq-Yq interchange resulting in supernormal X-linked gene expression in severely retarded males with 46,XYq- karyotype

The critical importance of dosage compensation is underscored by a novel human syndrome ("XYXq syndrome") in which we have detected partial X disomy, demonstrated supernormal gene expression resulting from the absence of X inactivation, and correlated this overexpression with its phenotypic consequences. Studies of three unrelated boys with 46,XYq- karyotypes and anomalous phenotypes (severe mental retardation, generalized hypotonia and microcephaly) show the presence of a small portion of distal Xq on the long arm of the Y derivative. Cells from these boys exhibit twice-normal activity of glucose-6-phosphate dehydrogenase, a representative Xq28 gene product. In all three cases, the presence of Xq DNA on a truncated Y chromosome resulted from an aberrant Xq-Yq interchange occurring in the father's germline.