XY gonadal dysgenesis and gonadoblastoma: a study in two sisters with a cryptic deletion of the Y chromosome involving the SRY gene

This paper reports a case of XY gonadal dysgenesis in two sisters. Both patients presented an eunochoid female phenotype with normal external genitalia. At laparotomy, the elder sister was found to have bilateral gonadoblastoma. Cytogenetic studies, which included G and C banding and in situ hybridization, showed that the patients had an apparently normal 46, XY karyotype. PCR analyses revealed absence of the conserved portion (HMG box) of the SRY gene and of the Y chromosome pseudoautosomal boundary region sequence in both patients. The presence of the ZFY sequence was detected by Southern hybridization in the two affected sisters. The patients' father (46, XY, no mosaicism detected in peripheral blood lymphocytes) was positive for SRY and ZFY sequences. The occurrence of gonadoblastoma is discussed in terms of the genetic factors that may lead to tumor development.     

Exclusion of the retinoblastoma gene and chromosome 13q as the site of a primary lesion for human breast cancer.

Chromosome 13q has been suggested as the site of a gene predisposing to human breast cancer, because loss of heterozygosity of alleles on this chromosome has been observed in some ductal breast tumors and because two breast cancer lines are altered at the retinoblastoma gene (RB1) at 13q14. To test this possibility, linkage of breast cancer susceptibility to 14 loci on chromosome 13q loci was assessed in extended families in which breast cancer is apparently inherited as an autosomal dominant trait. RB1 was excluded as the site of a breast cancer gene by a lod score of Z = -7.60 at close linkage for 13 families. Multipoint analysis yielded negative lod scores throughout the region between 13q12 and 13q34; over most of this distance, Z less than -2.0. Therefore, chromosome 13q appears to be excluded as the site of primary lesion for breast cancer in these families. In addition, comparison of tumor versus normal tissues of nonfamilial breast cancer patients revealed an alteration at the 5' end of RB1 in a mucoid carcinoma but no alterations of RB1 in five informative ductal adenocarcinomas. Linkage data and comparisons of tumor and normal tissues suggest that changes in the RBI locus either are secondary alterations associated with progression of some tumors or occur by chance.     

Molecular cytogenetic aberrations in Tunisian patients with multiple myeloma identified by cIg-FISH in fixed bone marrow cells

Cytogenetic studies in multiple myeloma (MM) are hampered by the hypo-proliferative nature of plasma cells. In order to circumvent this problem, we have used a combination of immunolabeling of cytoplasmic Ig light chains (λ or κ) and FISH (cIg-FISH), which allowed a comprehensive detection of the most common and/or recurrent molecular cytogenetic aberrations on fixed bone marrow cells of 70 Tunisian patients. Translocations involving the chromosome 14q32 region were observed in 32 cases (45.7%), including 18 cases with a t(11;14), 8 cases with a t(4;14), and 2 cases with a t(14;16). Deletions of the 13q14 region (D13S319/RB1) were detected in 18.6%, and deletions of the 17p13 region (TP53) in 5.7% of the cases, respectively. Of all patients with a D13S319/RB1 deletion, 61.5% also carried a 14q32 translocation, whereas TP53 deletions were associated with a t(11;14) in 2 cases (50%) and a D13S319 deletion in 1 case (25%). Our results suggest that there is a correlation between the presence of 14q32 translocations and chromosome 13q14 deletions in MM patients and that cIg-FISH is more sensitive as compared to conventional karyotyping in detecting molecular cytogenetic abnormalities in this disease.     

Marked differences in unilateral isolated retinoblastomas from young and older children studied by comparative genomic hybridization

Although it is established that the loss of function of both alleles of the RB1 gene is a prerequisite for the development of retinoblastoma, little is known about the genetic events that are required for tumor progression. We used comparative genomic hybridization (CGH) to search for DNA copy number changes in isolated unilateral retinoblastomas. From a series of 66 patients with retinoblastomas with somatic mutations in both RB1 alleles, tumor samples from 13 children with the youngest (2.0-9.8 months) and 13 with the oldest (36.2-84.1 months) age at operation were studied. Loss at 13q14, the location of RB1, was demonstrated in two tumors only. Recurring chromosome imbalances included gains at 6p (11/26), 1q (10/26), 2p (4/26), and 17q (4/26), gains of the entire chromosome 19 (3/26), and losses at 16q (9/26). A commonly gained region at 1q32 was identified. Increased dosage of GAC1, a candidate oncogene located in 1q32, was found in two of four tumors by Southern blot analysis. Comparison of the CGH findings revealed that retinoblastomas from children with an older age at operation showed significantly more frequent (13/13 cases vs 4/13 cases; P = 0.0005) and more complex genetic abnormalities (median, 5 changes/abnormal tumor vs median, 1.5 changes/abnormal tumor; P = 0.003) than retinoblastomas from children with a young age at operation. Gains at 1q, 2p, 17q, of the entire chromosome 19 and losses of 16q were restricted to the older age group. Our results suggest that the progression of retinoblastomas from older patients follows mutational pathways different from those of younger patients.     

Prenatal detection of an unstable ring 21 chromosome

Summary An unstable ring chromosome 21 detected through prenatal studies was associated at birth with an apparently normal male phenotype. At 14 months of age, examination indicated only minor developmental delay. The majority of cells examined from amniocyte, fibroblast, and lymphocyte cultures contained an asymmetrical dicentric ring 21 chromosome which was larger than a normal chromosome 21. This ring is presumed to be a duplication for most of chromosome 21 and a deletion of part of the terminal regions. The karyotype is described as mos45, XY,-21/46,XY,r(21)(p13q22.3). The child is monosomic for part of the sub-band 21q22.3 in every cell and trisomic for the remainder of the chromosome in most of his cells. The terminal deletion does not appear to have been severely detrimental to the phenotype and the effective trisomy present in many cells studies was insufficient to cause the Down syndrome.     

Chromosome abnormalities involving 11p13 and low erythrocyte catalase activity

Summary Two unrelated patients with clinical features of 11p13 deletion syndrome, 3 years old and 3 months old, are reported. The clinical features of the patients included mental retardation, aniridia, nystagmus, blepharophimosis, and genitourinary abnormalities. Both patients were apparently free from Wilms' tumor and gonadoblastoma. Prometaphase banding analyses revealed a 46,XY,del(11)(p 1300p 1500) karyotype in one patient and 46,XX,dir ins(11;2)(p13;q12q23) in the other. Catalase activities in the erythrocytes in the two patients were respectively 65% and 56% of those of normal controls, close to the expected values in hemizygosity of the catalase gene. These findings confirmed a close linkage of the gene for catalase and those for the aniridia-Wilms' tumor or gonadoblastoma complex.     

Molecular analysis of chromosome region 11p13 in patients with Drash syndrome

Summary The association of nephropathy, Wilms' tumour and genital abnormalities is known as Drash syndrome. Two of these features are also seen in the WAGR (Wilms' tumour, aniridia, genito-urinary abnormalities, mental retardation) complex, known to be associated with deletions of chromosome region 11p1S. We have carried out karyotypic and molecular studies in 10 Drash patients, 5 males and 5 females. All the males had a 46XY karyotype as did 3/5 of the phenotypic females, the other two having a 46XX karyotype. One of the 46XX females also had a deletion of region 11p13–p12, the only detectable autosomal chromosome abnormality in any of the patients studied. Lymphoblastoid cell lines were prepared from 6 of the Drash patients and were used in dosage studies using a variety of DNA probes from the 11p13 region. There was no evidence of microdeletions in any patient with a normal karyotype. Because of the 46XY karyotype in phenotypic females, selected X and Y chromosome loci were analysed and all found to be normal. Although Drash syndrome is likely to be of genetic origin, there are no readily detected deletions within the 11p13 region.     

Aniridia,male pseudohermaphroditism,gonadoblastoma, mental retardation,and del 11p13

Summary A 20-month-old male patient was referred because of severe growth and mental retardation, bilateral glaucoma, hypospadias, and cryptorchidism. Karyotyping revealed a de novo complex three-chromosome rearrangement as well as deletion of band 11p13:46,XY,t(4;7;15)(q212;p14;q26),del(11) (p13p14). Trabeculectomia revealed bilateral aniridia. Surgery on the genitalia revealed male pseudohermaphroditism and bilateral gonadoblastoma. The kidneys were normal. A deficiency in catalase (CAT) activity allowed the regional assignment of the CAT gene to band 11p13.     

Gonadoblastoma: molecular definition of the susceptibility region on the Y chromosome.

Using sequence-tagged sites we have performed deletion mapping of the Y chromosome in sex-reversed female patients with a Y chromosome and gonadoblastoma. The GBY gene (gonadoblastoma locus on the Y chromosome) was sublocalized to a small region near the centromere of the Y chromosome. We estimate the size of the GBY critical region to be approximately 1-2 Mb. Our analysis also indicates that copies of two dispersed Y-linked gene families, TSPY (testis-specific protein, Y-encoded) and YRRM (Y-chromosome RNA recognition motif) are present in all patients and that copies of TSPY but not YRRM fall within the GBY critical region as formally defined by deletion mapping. Two tumor samples showed expression of both genes and in one patient this expression was limited to a unilateral gonadoblastoma but absent in the contralateral streak gonad. Although our results do not directly implicate TSPY or YRRM in the etiology of the tumor, they raise the issue of whether there is one GBY gene in the critical region or possibly multiple GBY loci dispersed on the Y chromosome.     

无精和严重少精症患者的遗传缺陷分析——-附2例世界首报染色体异常核型

对217例无精和严重少精症患者外周血淋巴细胞染色体核型进行分析,并采用聚合酶链反应对7例Y染色体结构异常患者的AZFc区进行检测。发现187例无精症患者中检出异常核型77例（41.18%）（其中46,XY,t(6;14)(p21;p13),46,XY,t(8;12)(p21;q24)为世界首报核型）,主要涉及染色体异常（数目异常和结构异常）;染色体异态（Y染色体异态和9号染色体臂间倒位）及46,XX性反转;30例严重少精症患者中检出异常核型4例（13.33%）（结构异常和46,XX性反转）。由此可见,性染色体数目和结构异常是精子发生障碍的主要原因,其次常染色体的某些断裂点也可能影响精子发生。AZFc区的缺失与否与精子发生也有直接关系。     

Cytogenetic analysis of retinoblastoma: evidence for multifocal origin and in vivo gene amplification

Retinoblastoma (Rb) is an uncommon childhood tumor of the neural retina with a significant genetic component in its etiology. A small proportion of patients have a deletion in chromosome 13 encompassing band 13q14, an observation which permitted the assignment of the RB1 locus to this region. About 20% of Rb tumors exhibit microscopic deletions of band 13q14 or monosomy 13. Trisomy 1q and i(6p) have also been reported in a high percentage of tumors. We analyzed the chromosome complements from direct preparations of 10 Rb tumors derived from seven patients. Modal chromosome numbers ranged from 45 to 48, and occasional duplications of the genomes were noted. In general, the tumors were chromosomally stable, although karyotypic evolution and random chromosome loss were encountered. Consistent abnormalities included trisomy 1q, i(6p), 6q-, and del(13)(q12----14). One patient with bilateral Rb had three tumor clones (two in one eye and one in the other) with chromosome abnormalities unrelated in origin. A second patient with unilateral Rb had two tumor clones with chromosome abnormalities again unrelated in origin. These two patients provide some of the first cytogenetic evidence for the multifocal origin of primary Rb. In the untreated tumor of a third patient, a homogeneously staining region (HSR) was detected in 1p32, indicating gene amplication in vivo; previously, an HSR at this site has been reported in the established Rb cell line Y79.     

Prenatal diagnosis and molecular cytogenetic characterization of mosaic ring chromosome 13

We present prenatal diagnosis and molecular cytogenetic characterization of de novo mosaic r(13). A 32-year-old woman underwent amniocentesis at 18 weeks of gestation because of maternal anxiety. Amniocentesis revealed a karyotype of 46,XY,r(13)[33]/45,XY,-13[19]. aCGH on uncultured amniocytes at repeated amniocentesis detected a 4.22-Mb deletion at 13q34. Interphase FISH on 100 uncultured amniocytes showed the ratio of r(13):-13:idic r(13) as 85%:13%:2%. The cord blood had a karyotype of 46,XY,r(13)[91]/46,XY,idic r(13)[6]/45,XY,-13[3]. The placenta had a karyotype of 46,XY,mar(13)[31]/45,XY,-13[3]. Metaphase FISH confirmed that the marker chromosomes in placenta were derived from chromosome 13. aCGH on cultured placental cells detected a 77.81-Mb deletion at 13q13.3–q34. The fetus postnatally manifested facial dysmorphism. Prenatal diagnosis of r(13) should alert mosaicism for deletion/duplication of r(13) and distal 13q deletion. Fetoplacental chromosomal discrepancy of r(13) may exist in case of mosaic r(13) detected by amniocentesis.     

Distribution of sex chromosomes in dysgenetic gonads of mixed type

In a four-week-old child with female external and internal genitalia but with clitoris hypertrophy chromosome analysis from blood lymphocytes revealed a 46,XY karyotype. No deletion of Y chromosomal sequences was detected by PCR analysis of genomic DNA isolated from peripheral blood leucocytes. Because of the increased risk for gonadal tumours, gonadectomy was performed. Conventional cytogenetic analysis of the left dysgenetic gonad revealed a gonosomal mosaicism with a 45,X cell line in 27 of 50 metaphases. The dysgenetic left gonad demonstrated a significantly higher proportion (P = 0.005) of cells carrying a Y chromosome (46.3%) than the streak gonad from the right side (33.9%). Histomorphological examination of the left gonad revealed immature testicular tissue and rete-like structures as well as irregular ovarian type areas with cystic follicular structures. Interphase FISH analysis of the different tissues of this dysgenetic gonad demonstrated variable proportions of cells with an X and a Y chromosome. Whereas Sertoli cells and rete-like structures revealed a significantly higher proportion of XY cells in relation to the whole section of the dysgenetic gonad (P < 0.0001), almost all granulose-like cells carried no Y chromosome. The proportion of XY/X cells in theca-like cells and Leydig cells was similar to that of the whole dysgenetic gonad. In contrast to these findings, spermatogonia exclusively contained an XY constellation.     

Mechanisms of loss of heterozygosity in retinoblastoma.

Retinoblastoma (RB) tumors arise when both alleles of the RB1 gene are inactivated by two mutational events (M1 and M2). M1 can be an initial germline or somatic mutation; M2 is frequently loss of heterozygosity (LOH), which makes the cell homozygous or hemizygous for the original mutation. LOH is the major mechanism by which many cancers are initiated. To further delineate the mechanism of LOH, we screened a total of 37 RB tumors for LOH by Southern blot analysis. The tumors were from 17 bilaterally and 17 unilaterally affected patients. Nineteen of 30 informative tumors (63%) from 27 patients showed LOH. Proximal and distal flanking markers on chromosome 13 were informative in 13 tumors, allowing evaluation of the mechanisms by which LOH occurred. Mitotic recombination was implicated in 6 (46%) of the 13 tumors.     

Re-evaluation of the sublocalization of esterase D and its relation to the retinoblastoma locus by in situ hybridization

In situ hybridization of a cDNA probe for the esterase D gene (ESD) was carried out on human chromosomes. The probe hybridized most strongly to 13q14.2 and 13q14.3. This observation raises doubts concerning the most recently published assignment of ESD to 13q14.1. A deletion in an individual with retinoblastoma was reported to separate the closely linked ESD and retinoblastoma (RB1) loci, placing ESD proximal to RB1. Quantitative in situ hybridization studies of this deletion do not confirm this interpretation. Rather, they suggest that ESD is missing from the deleted chromosome 13 and duplicated on the normal homolog. From these findings, we conclude that the deletion in this individual cannot be used to determine the orientation nor the sublocalization of ESD and RB1 within the 13q14 region.     

46,XY phenotypic male with focal segmental glomerulosclerosis caused by the WT1 splice site mutation

OBJECTIVE: Frasier syndrome is characterized by progressive glomerulopathy due to nonspecific focal and segmental glomerulosclerosis (FSGS), 46,XY sex reversal and the development of gonadoblastoma from dysgenetic gonads. Donor splice site heterozygous mutations in intron 9 of the Wilms' tumor gene (WT1) cause this disease. We investigated whether WT1 mutations showed clinical heterogeneity. PATIENTS AND METHODS: A 6-year-old phenotypic boy was diagnosed as having FSGS. His karyotype was 46,XY. Gonadotropin-releasing hormone and human chorionic gonadotropin stimulation tests revealed normal luteinizing hormone, follicle-stimulating hormone and testosterone responses. The other patient was a 7-year-old 46,XY female with FSGS. Prophylactic gonadectomy was performed and gonadoblastoma was found. By polymerase chain reaction and direct sequencing, WT1 was analyzed in these patients. RESULTS AND CONCLUSION: Both patients had IVS9 + 5G-->A in intron 9 of the WT1. Our study indicates a normal 46,XY phenotypic male patient with FSGS. The phenotypic variations of the WT1 splice site mutations are further expanded.     

A Yeast Artificial Chromosome Contig That Spans the RB1-D13S31 Interval on Human Chromosome 13 and Encompasses the Frequently Deleted Region in B-cell Chronic Lymphocytic Leukemia

Abnormalities involving chromosome 13 have been reported as the only cytogenetic change in B-cell chronic lymphocytic leukemia (BCLL). Deletions are the most common cytogenetic abnormality and always involve 13q14, but when translocations are seen, the consistent breakpoint is always in 13q14. It is now established that deletions, distal to the RB1 gene in 13q14, are invariably associated with these translocations. We have recently described the smallest such deletion from a series of rearrangements from these tumors isolated in somatic cell hybrids, which spans approximately 1 Mb. In this report, we present the results of a series of a chromosome walking experiments using YACs and have been able to span this small deletion, which must contain the gene that is frequently deleted in BCLL. Four probes from 13q14 (RBI-mgg15-D13S25-D13S31) were used to isolate corresponding YACs for each of the markers. The chromosomal location of these YACs was verified using FISH, which also demonstrated their nonchimeric nature. Vectorette end rescue was then used to demonstrate the overlap of the YACs and to isolate new clones to complete the contig. The extremes of the contig were shown to cross the chromosome 13 translocation breakpoints isolated in somatic cell hybrids that carry the derivatives of chromosome 13 involved in the smallest BCLL deletion. This YAC contig covers the entire deletion and will prove a valuable resource to begin isolating genes from this region. In addition, we have isolated YACs corresponding to the RB1 locus, which extends the contig over a 3.8-cM distance on the chromosome.     

Allelotype of human thyroid tumors: loss of chromosome 11q13 sequences in follicular neoplasms.

Two classes of genes are the targets of mutations involved in human tumorigenesis: oncogenes, the activation of which leads to growth stimulation, and tumor suppressor genes, which become tumorigenic through loss of function, often through allelic deletion. To obtain evidence for a role for tumor suppressor genes in thyroid tumorigenesis, we examined DNA from 80 thyroid neoplasms for loss of heterozygosity in multiple chromosomal loci using 19 polymorphic genomic probes. None of the informative thyroid tumors studied had allelic loss detected with probes for chromosome 2q (D2S44), 3p (D3F15S2, D3S32), 3q (D3S46), 4p (D4S125), 6p (D6S40), 8q (D8S39), 9q (D9S7), 12p (D12S14), 13q (D13S52), 17p (D17S30), or 18q (D18S10). One of eight of the follicular adenomas had a 10q deletion detected with marker D10S15, and one of 26 had a 10q deletion detected with D10S25. One of two of the follicular carcinomas had an 11p deletion in the H-ras locus. The most significant findings were on chromosome 11q13, the site containing the putative gene predisposing to multiple endocrine neoplasia type I. Four of 27 follicular adenomas had loss of heterozygosity for probes in this region. Allelic deletions were detected with the following probes: D11S149, PYGM, D11S146, and INT2. None of 13 informative papillary carcinomas and none of two follicular carcinomas had loss of heterozygosity detectable with these 11q13 markers. Allelic loss is a relatively infrequent event in human thyroid tumors. Deletions of chromosome 11q13 are present in about 14% of follicular, but not papillary, neoplasms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Interstitial deletion of 16(q13q22) in a newborn resulting from a paternal insertional translocation.

A dysmorphic newborn showed an interstitial deletion of the long arm of a chromosome 16 due to a balanced paternal insertional translocation 46,XY,ins(14;16)(q23;q13q22). The insertion was confirmed by chromosomal in situ suppression (CISS-) hybridization. Clinical features considered to be typical for a 16q- phenotype are demonstrated in this patient. Similar observations described in the literature are compared and discussed with reference to the phenocritical region.     

Molecular analysis of 46,XY females and regional assignment of a new Y-chromosome-specific probe

Summary The relationship between Y-chromosome abnormalities and gonadal differentiation was investigated in six phenotypic females with a 46,XY karyotype and one patient with ambiguous genitalia secondary to apparently nonmosaic 46,XY mixed gonadal dysgenesis. No alterations were found in the Y chromosomes of six of these individuals by the use of either cytogenetic or molecular techniques. Cytogenetic analysis with high-resolution G-banding and Q-banding revealed a small deletion in the short arm of the Y chromosome in one female patient with some features of Turner syndrome. Southern hybridization with Y-specific probes showed a loss of DNA within deletion intervals 1, 2, and 3 of the Y chromosome. A new Y-chromosome-specific DNA probe that hybridizes to deletion interval 3 is described.