1/606. 'Identical' twins with discordant karyotypes.A chromosomal abnormality in one of the fetuses of a monozygotic twin pregnancy is a rare phenomenon. In the prenatal unit of our cytogenetics laboratory we have recently come across two such heterokaryotypic twin pregnancies. In both cases ultrasound abnormalities were detected in one fetus of each twin pair. Chromosomal analysis showed that one twin pregnancy was discordant for trisomy 21 and the other for 45,X. Ultrasonographic examination suggested a monochorionic twin pregnancy in each case and dna studies confirmed that both sets of twins were monozygotic. Both pregnancies were terminated. Biopsies taken from different sites of the placentas showed chromosomal mosaicism in both cases. There was no clear correlation between the karyotype found close to the site of the umbilical cord insertion in the placenta and the karyotype of the fetus. Sampling of amniotic fluid from both sacs is recommended in diamniotic twin pregnancies if one (or both) of the fetuses has ultrasound abnormalities, even if the twins are apparently monochorionic.- - - - - - - - - - ranking = 1keywords = gene (Clic here for more details about this article) |
2/606. prenatal diagnosis of 46,XX male fetuses.ultrasonography can accurately determine phenotypic sex differences from those of the genetic sex. Two cases were identified; they were the result of a translocation of the SRY gene from the y chromosome to the x chromosome during meiosis. An ultrasonographic difference may represent an otherwise unsuspected genetic abnormality.- - - - - - - - - - ranking = 3keywords = gene (Clic here for more details about this article) |
3/606. De novo duplication xq22-q23 in a girl with short stature and gonadal dysgenesis.A female of 20 years of age with short stature, gonadal dysgenesis and Turner stigmata with a de novo dup Xq22-q23 was studied. The maternal cytogenetic study was normal. This case represents the smallest Xq duplication in an abnormal female. We discuss the possibility of a maternal imprinting.- - - - - - - - - - ranking = 6keywords = gene (Clic here for more details about this article) |
4/606. Leri-Weill syndrome as part of a contiguous gene syndrome at Xp22.3.We report on a mother and her 5-year old son, both with a terminal deletion of the short arm of the x chromosome. By molecular genetic analysis the breakpoint was located distal to steroid sulfatase gene. The boy manifested, due to nullisomy of this region, short stature (SHOX), chondrodysplasia punctata (ARSE), and mental retardation (putative mental retardation gene MRX 49). Short stature is present in mother and son, but both also had bilateral Madelung deformity, a key finding in the Leri-Weill syndrome.We discuss the phenotype in relationship to hitherto published cases with chromosomal aberrations and contiguous gene syndromes of Xp22.3.- - - - - - - - - - ranking = 6775.9953748195keywords = contiguous gene syndrome, gene syndrome, retardation, mental retardation, contiguous gene, gene (Clic here for more details about this article) |
5/606. Maternally inherited cardiomyopathy: clinical and molecular characterization of a large kindred harboring the A4300G point mutation in mitochondrial deoxyribonucleic acid.OBJECTIVES: The purpose of this study was to describe the clinical and molecular features of a large family with maternally inherited cardiomyopathy (MICM). BACKGROUND: Recently, several mitochondrial deoxyribonucleic acid (mtDNA) point mutations have been associated with MICM. However, the distinctive clinical and morphologic features of MICM are not fully appreciated. This is partially due to the small size of the reported pedigrees, often lacking detailed clinical and laboratory information. methods: Clinical and genetic analysis of the family was carried out. RESULTS: echocardiography showed mostly symmetrical hypertrophic cardiomyopathy in 10 family members. The illness had an unfavorable course. Progressive heart failure occurred in three subjects, who eventually died; one individual underwent heart transplantation. Electrocardiographic or echocardiographic signs of cardiac hypertrophy in the absence of significant clinical complaints were observed in five subjects. neurologic examination was normal. The mutation was detected in blood from all available subjects. Abundance of mutated molecules ranged between 13% and 100% of total mtDNA genomes. The severity of the disease could not be foreseen by the proportion of mutation in blood. CONCLUSIONS: This report contributes a better description of the clinical aspects of MICM and provides important clues to distinguish it from hypertrophic cardiomyopathy. We suggest that mtDNA mutations, particularly in the transfer ribonucleic acid for isoleucin, should be systematically searched in patients with MICM. The identification of an underlying maternally inherited mitochondrial dna defect in familial cases of cardiomyopathy may considerably influence the management and genetic counseling of affected patients.- - - - - - - - - - ranking = 2keywords = gene (Clic here for more details about this article) |
6/606. Risk of gonadoblastoma in female patients with y chromosome abnormalities and dysgenetic gonads.We report two female patients with gonadal dysgenesis and sex chromosome mosaicism involving the y chromosome. Conventional karyotyping was supplemented with fluorescent in situ hybridisation techniques in order to confirm the presence of Y chromosomes. One patient is a phenotypic female with karyotype 45,X/46,X,idic(Y)(q11.2). She underwent a laparoscopic gonadectomy at which streak ovaries without evidence of gonadoblastoma were removed. The second patient presented as a virilised female with karyotype 45,X/47,XYY. At laparoscopy, she was found to have mixed gonadal dysgenesis with a gonadoblastoma in situ. We recommend early gonadectomy in female children presenting with gonadal dysgenesis and the presence of a y chromosome although once the gonadoblastoma locus on y chromosome gene has been cloned it may be possible to identify those patients who have a low risk of developing gonadoblastoma.- - - - - - - - - - ranking = 8keywords = gene (Clic here for more details about this article) |
7/606. fragile x syndrome and an isodicentric x chromosome in a woman with multiple anomalies, developmental delay, and normal pubertal development.We report on an individual with developmental delays, short stature, skeletal abnormalities, normal pubertal development, expansion of the fragile X triplet repeat, as well as an isodicentric x chromosome. S is a 19-year-old woman who presented for evaluation of developmental delay. pregnancy was complicated by a threatened miscarriage. She was a healthy child with intellectual impairment noted in infancy. Although she had global delays, speech was noted to be disproportionately delayed with few words until age 3.5 years. Facial appearance was consistent with fragile x syndrome. age of onset of menses was 11 years with normal breast development. A maternal male second cousin had been identified with fragile x syndrome based on dna studies. The mother of this child (S's maternal first cousin) and the grandfather (S's maternal uncle) were both intellectually normal but were identified as carrying triplet expansions in the premutation range. S's mother had some school difficulties but was not identified as having global delays. Molecular analysis of S's fragile X alleles noted an expansion of more than 400 CGG repeats in one allele. Routine cytogenetic studies of peripheral blood noted the presence of an isodicentric X in 81of 86 cells scored. Five of 86 cells were noted to be 45,X. Cytogenetic fra(X) studies from peripheral blood showed that the structurally normal chromosome had the fragile site in approximately 16% of the cells. Analysis of maternal fragile X alleles identified an allele with an expansion to approximately 110 repeats. FMRP studies detected the expression of the protein in 24% of cells studied. To our knowledge, this is the first patient reported with an isodicentric X and fragile x syndrome. Whereas her clinical phenotype is suggestive of fragile x syndrome, her skeletal abnormalities may represent the presence of the isodicentric X. Treatment of S with 20 mg/day of Prozac improved her behavior. In the climate of cost con trol, this individual reinforces the recommendation of obtaining chromosomes on individuals with developmental delay even with a family history of fragile x syndrome.- - - - - - - - - - ranking = 2keywords = gene (Clic here for more details about this article) |
8/606. Deletion of y chromosome involving the DAZ (deleted in azoospermia) gene in XX males.The testicular histology and the presence or absence of 32 Y dna loci was investigated, with a focus on the long arm of y chromosome (Yq) interval 6, by means of a polymerase chain reaction strategy in 2 XX males. seminiferous tubules lined by only sertoli cells and a slight thickening of tubular walls were observed. The men showed an absence of 32 Y dna loci. These facts suggest that severe spermatogenic impairment is caused by deletions of Yq interval 6 in XX males.- - - - - - - - - - ranking = 4keywords = gene (Clic here for more details about this article) |
9/606. Random X-inactivation in a girl with duplication Xp11.21-p21.3: report of a patient and review of the literature.We describe a 10-month-old girl with abnormal clinical findings and Xp duplication. She showed poor weight gain and developmental retardation, and had several minor anomalies including pigmentary dysplasia (hypomelanosis of Ito). She had a partial short arm duplication in the paternally derived x chromosome, 46,X,dup(X)(p11. 21p21.3), with the normal and duplicated X chromosomes randomly inactivated. These findings indicate that gross functional imbalance in the cells with an active dup(X) chromosome has caused global developmental defects in the patient, and that functional chromosomal mosaicism with respect to the duplicated Xp region has resulted in pigmentary dysplasia. literature review of 52 patients with partial X duplications revealed (1) random or skewed but not completely selective X-inactivation in 9 of 45 patients examined for the X-inactivation pattern, independently of the size or location of duplicated segments, (2) apparently normal phenotype in 6 of 9 patients with random or skewed X-inactivation, and (3) an abnormal phenotype in 13 of 35 patients with completely selective inactivation of dup(X) chromosomes.- - - - - - - - - - ranking = 252.46313925608keywords = retardation, mental retardation (Clic here for more details about this article) |
10/606. 45,X/46,X,r(Y) karyotype transmitted by father to son after intracytoplasmic sperm injection for oligospermia. A case report.BACKGROUND: The advent of assisted reproductive techniques, such as intracytoplasmic sperm injection (ICSI), has permitted conception and successful pregnancy for an increasing population of infertile men. Approximately 13.7% of infertile men with aspermia and 4.6% with oligospermia have a coexistent chromosome abnormality. Although the ICSI procedure appears safe thus far, early studies are in progress to evaluate outcomes of such pregnancies. For men whose infertility is linked to genetic conditions, it is an unprecedented challenge to predict the potential effects on their offspring. CASE: At 18 weeks' gestation, a 45,X/46,X,r(Y) karyotype was found on genetic amniocentesis performed for advanced maternal age. The pregnancy was achieved by ICSI using sperm from the husband, who was infertile due to severe oligospermia. Subsequently the same karyotype was found in the father. To our knowledge, this is the first reported case of familial transmission of ring y chromosome. CONCLUSION: It is strongly recommended that ICSI and other new assisted reproductive techniques be preceded by genetic screening for male infertility as well as other indications warranted by the family history since traditional risk assessment may require revision and outcomes may be uncertain in some cases.- - - - - - - - - - ranking = 3keywords = gene (Clic here for more details about this article) |
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