Pathogenetics of 45,X/46,XY gonadal mosaicism

Five patients with 45,X/46,XY mosaicism ranging from 8% to 66% of 46, XY lymphocytes in the peripheral blood were studied. Their age when chromosome studies were performed ranged from a few days to 37 yr. The phenotypic presentations were two females with gonadal dysgenesis and Turner syndrome features (cases 1 and 2), two males with ambiguous genitalia and mixed gonadal dysgenesis (cases 3 and 4), and an infertile male with an atrophic testis (case 5). Fluorescence in situ hybridization (FISH) using dual-color X and Y probes on paraffin-embedded sections of the gonads was performed to assess mosaicism. A mosaic cell line with a Y chromosome was present in the streak ovary, dysgenetic gonad, and testis. In the mixed gonadal dysgenesis cases (cases 3 and 4), the testis had a higher percentage (greater than two fold) of XY cells than the ovary had. However, the highest ratio of cells with a Y chromosome was in the atrophic testis of the infertile male (case 5). The distribution of mosaic clones in the different gonadal cell types was examined. Both females (cases 1 and 2) with dysgenetic gonads had scant ovarian stroma and nests of Leydig or hilus cells. In FISH studies, the coelomic epithelial cells were predominantly 46,XY; in comparison, the Leydig and hilus cells had a lower percentage and the ovarian stroma the least number of cells with a Y signal. A mixed gonadal dysgenesis case (case 3) possessed a right testis with an XY complement in approximately 21% of Sertoli cells and approximately 14% of Leydig cells. The infertile male had an atrophic testis with interstitial hyperplasia (case 5). His testis contained Sertoli cells but no evidence of spermatogenesis. FISH detected a Y signal in about 50-60% of the Sertoli and Leydig cells.     

Prenatal identification of mos 45,X/46,X,+mar in a normal male baby by cytogenetic and molecular analysis

We report a case of mos 45,X/46,X,+mar, diagnosed prenatally by amniocentesis, whose physical examination, including external and internal organs, along with serum testosterone values were normal five years after delivery. The mosaic karyotype was seen in 146 of 240 cells examined (amniotic fluid cells, 110/65; placental chorionic villi: 5/4; cord blood, 21/81; cultured skin fibroblasts, 10/90) from 386 metaphases, and the marker chromosome appeared as a small non-fluorescent acrocentric chromosome. All autosomes appeared normal, and no normal Y chromosome could be demonstrated. Analysis of 26 Y-chromosome loci by molecular techniques such as PCR, Southern analysis using multiple Y-specific DNA probes, and Hae III restriction endonuclease assessment of male-specific repeated DNA in the heterochromatic region of the Y chromosome, and fluorescence in situ hybridization (FISH), revealed the marker was derived from a Y chromosome including p terminal to q11.23, and paracentric inversion in the remaining Y long arm. The formation of testes can be considered as existence of SRY (sex-determining region of Y) as a testis-determining factor. The present report illustrates the importance of FISH and molecular techniques as a complement to cytogenetic methods for accurate identification and characterization of chromosome rearrangements in prenatal diagnosis.     

Prenatal diagnosis of ring chromosome 6 in a fetus with hydrocephalus

A patient with ring chromosome 6/monosomy 6 mosaicism is presented. At 25 weeks' gestation, ultrasound examination demonstrated fetal hydrocephalus. Amniocentesis was performed. The fetal karyotype was 45,XY,-6/ 45,XY,-6,+f/46,XY,r(6)(p25q27). Delivery of this male infant was by Caesarean section at 37 weeks' gestation. The karyotype in peripheral blood lymphocytes was 46,XY,r(6)(p25q27) with no indications of mosaicism. The infant had hydrocephalus which required treatment with a ventriculoperitoneal shunt at 22 days of age. He had no other obvious serious congenital anomalies. By 17 months he had developed microcephaly, seizures, severe bilateral hearing loss, and global development delay. This patient provides information regarding phenotypic variability of ring chromosome 6 and also reinforces the importance of offering amniocentesis if fetal hydrocephalus is detected as an isolated anomaly.     

46,XY/46,XY,21q- mosaicism in an infant with neutropenia and properdin deficiency

An infant with neutropenia, properdin deficiency, and a 46,XY/46,XY,21q- mosaicism is described. It is not known whether these two findings are related to the missing 21q material. The propositus is normal in appearance, and has none of the phenotypic features associated with the G-group deletion syndromes.     

Primed in situ labeling for rapid prenatal diagnosis

OBJECTIVE: Our purpose was to assess the feasibility of primed in situ labeling for analysis of prenatal diagnostic specimens. STUDY DESIGN: Prenatal diagnostic specimens were chosen at random for analysis without knowledge of clinical indication. Primed in situ labeling with primers for chromosomes 18, 21, X, and Y was performed separate from conventional cytogenetic analyses. All clinical management considerations were based solely on conventional cytogenetic analyses. RESULTS: Forty-one samples were analyzed by primed in situ labeling: 35 direct preparations of chorionic villi and 6 uncultured amniotic fluid samples. In all cases analysis confirmed the particular chromosome number determined by conventional cytogenetic analysis. CONCLUSIONS: Although conventional metaphase studies remain the standard for prenatal cytogenetic analyses, the preliminary feasibility study finds primed in situ labeling to be a rapid and reliable adjunctive diagnostic technique applicable for prenatal diagnosis in certain clinical situations. Further study is needed to assess the efficacy of primed in situ labeling in comparison to fluorescent in situ hybridization and conventional cytogenetic analyses for prenatal diagnoses.     

Is serum thyroglobulin a useful marker for thyroid cancer in patients who have not had ablation of residual thyroid tissue?

Among 58,000 amniocenteses completed, our laboratories found one case of true cytogenetic trisomy 2 mosaicism in a fetus with multiple abnormalities. In contrast, 11 fetuses phenotypically normal at birth were found to have true trisomy 2 mosaicism in their chorionic villus cells among the 10,500 fetuses tested by chorionic villus sampling (CVS). In our single abnormal case, amniocentesis performed at 19 weeks after finding an elevated maternal serum AFP found two independent cultures with trisomy 2 karyotypes in 8 of 25 and 7 of 31 amniocytes, respectively. Although oligohydramnios was noted by ultrasound, the mother elected to continue the pregnancy. At 26 weeks the fetus had intrauterine growth retardation (IUGR), hydronephrosis, and cardiac abnormalities. When delivered by Cesarean section at 30 weeks, the infant had multiple anomalies and developed necrotizing enterocolitis and severe cholestasis. At 5 months coronal magnetic resonance imaging (MRI) displayed delayed myelination and abnormal brain morphology. The patient also exhibited significant growth failure and developmental delay. Although chromosomes were normal in blood, skin fibroblasts, and ascites fluid cells, 4 of 100 hepatic biopsy fibroblasts were 47,XY,+2. Molecular analysis excluded uniparental disomy (UPD) of chromosome 2 in the 46,XY cell line. This and other reports of rare phenotypically abnormal trisomy 2 mosaic fetuses identified by karyotyping amniocytes emphasizes the substantially higher fetal risk of abnormal development than when trisomy 2 is found only in chorionic villus cells.     

Familial ring (19) chromosome mosaicism: case report and review

Ring (19) chromosomal mosaicism has been identified in a 14-month-old girl referred for cytogenetic evaluation due to microcephaly and developmental delay with autistic-like mannerisms. An analysis of her peripheral blood lymphocytes showed a 46,XX,r(19) cell line in 119/121 of cells examined. Of the two remaining cells, one had a normal female chromosome complement and the other showed loss of one of the chromosome 19 homologs. Further analysis by fluorescence in situ hybridization using an all human telomere probe showed the presence of a single hybridization signal on the r(19) chromosome. Subsequent cytogenetic characterization of cells derived from the patient's phenotypically normal mother also demonstrated the presence of a ring 19 chromosome in 4/100 cells. The remaining cells had a normal female chromosome complement. These findings represent the first reported case of familial ring 19 mosaicism. The cytogenetic and clinical findings in these two individuals are discussed in relation to six previously reported cases of de novo ring chromosome 19 mosaicism.     

Chromosome polymorphisms in karyotypes from amniotic fluid cell cultures

Frequencies of 12 fluorescent chromosome polymorphisms were scored from Q-banded karyotypes derived from 108 midtrimester diagnostic amniotic fluid cell cultures. The most frequent variants were the bright fluorescent short arm of chromosome 13 (P = 0.458) and the bright fluorescent marker close to the centromere on chromosome 3 (P = 0.426).The polymorphism pattern was found to be different between the maternal (blood culture) and fetal (amniotic fluid cell culture) karyotypes in each of the 25 paired cases studied. This technique is valuable in prenatal diagnosis to exclude possible maternal cell contamination and outgrowth in cases where the amniotic fluid cell cultures reveal a female karyotype.     

Daily energy metabolism in patients with type 1 diabetes mellitus

The availability of markers for the 17p11.2 region has enabled the diagnosis of Smith-Magenis syndrome (SMS) by fluorescence in situ hybridization (FISH). SMS is typically associated with a discernible deletion of band 17p11.2 upon cytogenetic analysis at a resolution of 400-550 bands. We present a case that illustrates the importance of using FISH to confirm a cytogenetic diagnosis of del(17)(p11.2). Four independent cytogenetic analyses were performed with different conclusions. Results of low resolution analyses of amniocytes and peripheral blood lymphocytes were apparently normal, while high resolution analyses of peripheral blood samples in two laboratories indicated mosaicism for del(17)(p11.2). FISH clearly demonstrated a 17p deletion on one chromosome of all peripheral blood cells analyzed and ruled out mosaicism unambiguously. The deletion was undetectable by flow cytometric quantitation of chromosomal DNA content, suggesting that it is less than 2 Mb. We conclude that FISH should be used to detect the SMS deletion when routine chromosome analysis fails to detect it and to verify mosaicism.     

A sex reversal infant with XX karyotype and complete male external genitalia

The unusual case of a Japanese newborn XX male is presented. Examination of chromosomes in amniotic fluid cells had shown a normal female karyotype (46,XX), but ultrasonography revealed a penis and a scrotum. The neonate had normal male external genitalia, and serum levels of luteinizing hormone, follicle stimulating hormone, and testosterone were all within the normal range. High resonance chromosome analysis revealed an excess portion on the short arm of one of the X chromosomes. We examined his genomic DNA by polymerase chain reaction (PCR) and detected two Y specific regions in his genomic DNA, the sex-determining region Y (SRY) and pseudoautosomal boundary Y. Nucleotide sequencing of the PCR products of SRY indicated no mutation. These findings suggested that the translocation or insertion of an SRY region on the X chromosome led to the development of testicles and a male phenotype.     

Constitutional mosaicism for a chromosome 9 inversion resulting in recombinant aneusomy in an offspring

We report on a case of constitutional mosaicism for a large pericentric inversion of chromosome 9 in a man whose daughter had recombinant aneusomy resulting in partial 9q duplication and partial 9p deletion. At age 6 months, the girl was evaluated because of congenital anomalies [corrected] and developmental delay. Chromosomal analysis on this infant showed a derivative chromosome 9 which was later determined to be a recombinant chromosome with trisomy of 9q34.1-->qter and monosomy of pter-->9p24. Chromosomal analysis in her father showed the presence of two cell lines; 75% of lymphocytes had a 46,XY pattern, and 25% had a 46,XY,inv(9)(p24q34.1) karyotype. The infant's physical findings represent a composite of the reported cases of both trisomy 9q34.1-->qter and monosomy pter-->9p24. The infant's father was phenotypically and cognitively normal. This case broadens the spectrum of reported cases of mosaicism for an autosomal structural rearrangement generating unbalanced gametes, and further supports the tenet that constitutional mosaicism has clinical relevance for genetic counseling.     

True trisomy 15 mosaicism, detected by amniocentesis at 12 weeks of gestation and fetal echocardiography

A case of mosaicism of trisomy 15, with two-thirds of the cells trisomic, was detected at 12 weeks of gestation in amniotic fluid cell cultures obtained with the filtration technique. Ultrasound examination at 13 weeks showed a nodule protruding into the amniotic cavity which was speculated to be remnants of a co-twin, causing the trisomic cell line. At 20 weeks of gestation, a malformation scan (level III) was normal, but supplementary fetal echocardiography revealed a severe cardiac defect (mitral atresia and a ventricular septal defect). Fetal lymphocytes obtained by cordocentesis showed trisomy 15 mosaicism, but only in 5 per cent of the mitoses. After termination, the same percentage of trisomy 15 mosaicism was found in cells from skin and tendon as in the original early amniocentesis. No sign of earlier twinning was found in the placenta or membranes. We conclude that mosaicism in early amniotic fluid obtained by the filter technique in this case reflected the true karyotype accurately and that supplementary echocardiography added significantly to the interpretation of the clinical implications.     

Receptor-activated Ca2+ influx via human Trp3 stably expressed in human embryonic kidney (HEK)293 cells. Evidence for a non-capacitative Ca2+ entry

Gonadal differentiation involves a complex interplay of developmental pathways. The sex determining region Y (SRY) gene plays a key role in testis determination, but its interaction with other genes is less well understood. Abnormalities of gonadal differentiation result in a range of clinical problems. 46,XY complete gonadal dysgenesis is defined by an absence of testis determination. Subjects have female external genitalia and come to clinical attention because of delayed puberty. Individuals with 46,XY partial gonadal dysgenesis usually present in the newborn period for the valuation of ambiguous genitalia. Gonadal histology always shows an abnormality of seminiferous tubule formation. A diagnosis of 46,XY true hermaphroditism is made if the gonads contain well-formed testicular and ovarian elements. Despite the pivotal role of the SRY gene in testis development, mutations of SRY are unusual in subjects with a 46,XY karyotype and abnormal gonadal development. 46,XX maleness is defined by testis determination in an individual with a 46,XX karyotype. Most affected individuals have a phenotype similar to that of Klinefelter syndrome. In contrast, subjects with 46,XX true hermaphroditism usually present with ambiguous genitalia. The majority of subjects with 46,XX maleness have Y sequences including SRY in genomic DNA. However, only rare subjects with 46,XX true hermaphroditism have translocated sequences encoding SRY. Mosaicism and chimaerism involving the Y chromosome can also be associated with abnormal gonadal development. However, the vast majority of subjects with 45,X/46,XY mosaicism have normal testes and normal male external genitalia.     

The anesthesiologic risk patient. Preoperative evaluation, intraoperative management and postoperative monitoring

A cryptorchid mouse with a 39,X/40,XY chromosome constitution was identified among 414 offspring born in the departmental XO mouse breeding colony. This mouse had a small testis on the left, with no sign of spermatogenesis, and a normal ovary on the right with several corpora lutea.     

Standardized AgNOR analysis: its usefulness in surgical oncology

Smith-Magenis syndrome (SMS) is a multiple congenital anomalies/mental retardation syndrome associated with deletion of band p11.2 of chromosome 17. The deletion is typically detected by high-resolution cytogenetic analysis of chromosomes from peripheral lymphocytes. Fluorescence in situ hybridization (FISH) has been previously used to rule out apparent mosaicism for del(17)(p11.2p11.2) indicated by routine cytogenetics. We now report mosaicism for del(17)(p11.2p11.2) in a child with SMS. The mosaicism had gone undetected during previous routine cytogenetic analysis. FISH analysis of peripheral lymphocytes as well as immortalized lymphoblasts using markers from 17p11.2 revealed that approximately 60% of cells carried the deletion. To our knowledge, this is the first case of SMS associated with mosaicism for del(17)(p11.2p11.2).     

Confined placental mosaicism for trisomy 8 and intra-uterine growth retardation

This report describes a case of apparent confined placental mosaicism for trisomy 8 in a pregnancy which produced a male infant with intra-uterine growth retardation. Postnatal cytogenetic and molecular studies were consistent with biparental disomy 8. Postnatally, the infant experienced a period of rapid catch-up growth and exhibited no clinical features of trisomy 8 mosaicism. His development was age appropriate.     

Agonist and antagonist actions of (-)pindolol at recombinant, human serotonin1A (5-HT1A) receptors

Prenatal diagnosis and clinical follow up of a patient with mosaicism for anomalies of chromosome 18 are reported. The fetus appeared on ultrasound to have multiple anomalies, including clubbed feet, abnormal hand positioning, edema of the scalp, cleft palate, and polyhydramnios. The karyotype on amniocytes was 47,XY,+i(18p). Postnatally, the peripheral blood karyotype was 46,XY,+i(18q), whereas the skin fibroblast karyotype was 47,XY,+i(18p). The infant had many features consistent with those previously described in cases of tetrasomy 18p and some that were consistent with trisomy 18q.     

Prenatal exclusion of segmental trisomy in familial chromosome 21 pericentric inversion by fluorescence in situ hybridization

We report the prenatal exclusion of partial trisomy in a family with maternal pericentric inversion of chromosome 21 by fluorescence in situ hybridization (FISH). After determining the structural rearrangement in the mother and her affected son with 46,XY,rec(21)dup(21q)inv(21)(p11q22) resulting in Down syndrome (DS), a chorionic villus sample from the current pregnancy was analysed for the copy number of the DS critical region with a cosmid contig. The signal distribution was normal and the cytogenetic analysis revealed that the fetus had inherited the inverted chromosome 21 in a balanced form. FISH probes specific for the DS region are of great value in supporting cytogenetic results, regardless of the structural status of chromosome 21.     

Prenatal detection of chromosome aneuploidies in uncultured chorionic villus samples by FISH

We developed a 1-d FISH assay for detection of numerical chromosome abnormalities in uncultured chorionic villus samples (CVS). Probes specific for chromosomes 13, 18, 21, X, and Y were used to determine ploidy by analysis of signal number in hybridized nuclei. Aneuploidy detection using this assay was directly compared with the results obtained by conventional cytogenetic analysis in a consecutive, clinical study of 2,709 CVS and placental samples. The FISH assay yielded discrete differences in the signal profiles between cytogenetically normal and abnormal samples. On the basis of these results, we generated FISH-assay cutoff values that discriminated between karyotypically normal and aneuploid samples. Samples with mosaicism and a single sample with possible heritable small chromosome X probe target were exceptions and showed poor agreement between FISH results and conventional cytogenetics. We conclude that the FISH assay may act as a more accurate and less labor-demanding alternative to "direct" CVS analysis.     

Low-level mosaicism for both trisomy 15 and monosomy-X in amniotic fluid cells confirmed in fetal tissues

We report here a case of true fetal mosaicism for both trisomy 15 and monosomy-X; the aberrant cell lines were initially detected at amniocentesis as low-level mosaicism (trisomy 15) and multiple-cell pseudo-mosaicism (monosomy-X). In the fetal lymphocytes, only metaphases with a normal chromosome complement were observed. After termination of the pregnancy, various fetal biopsies revealed both trisomy 15 and monosomy-X mosaicism, whereas, at autopsy, no external or internal abnormalities could be detected in the fetus. The karyotype can be described as 45,X[15]/47,XY,+15[3]/46,XY[27]. Our results implicate that an additional amniocentesis could be more helpful than fetal blood sampling in predicting the fetal karyotype after diagnosis of chromosome mosaicism at amniocentesis.