Recombination in the pseudoautosomal region in a 47,XYY male.

Males with a 47,XYY karyotype generally have chromosomally normal children, despite the high theoretical risk of aneuploidy. Studies of sperm karyotypes or FISH analysis of sperm have demonstrated that the majority of sperm are chromosomally normal in 47,XYY men. There have been a number of meiotic studies of XYY males attempting to determine whether the additional Y chromosome is eliminated during spermatogenesis, with conflicting results regarding the pairing of the sex chromosomes and the presence of an additional Y. We analyzed recombination in the pseudoautosomal region of the XY bivalent to determine whether this is perturbed in a 47,XYY male. A recombination frequency similar to normal 46,XY men would indicate normal pairing within the XY bivalent, whereas a significantly altered frequency would suggest other types of pairing such as a YY bivalent or an XYY trivalent. Two DNA markers, STS/STS pseudogene and DXYS15, were typed in sperm from a heterozygous 47,XYY male. Individual sperm (23,X or Y) were isolated into PCR tubes using a FACStarPlus flow cytometer. Hemi-nested PCR analysis of the two DNA markers was performed to determine the frequency of recombination. A total of 108 sperm was typed with a 38% recombination frequency between the two DNA markers. This is very similar to the frequency of 38.3% that we have observed in 329 sperm from a normal 46,XY male. Thus our results suggest that XY pairing and recombination occur normally in this 47,XYY male. This could occur by the production of an XY bivalent and Y univalent (which is then lost in most cells) or by loss of the additional Y chromosome in some primitive germ cells or spermatogonia and a proliferative advantage of the normal XY cells.

Neuropsychological and functional cognitive skills of 35 unselected adults with sex chromosome abnormalities.

This report presents data defining the neuropsychological and cognitive phenotypes of a group of adults with sex chromosome abnormalities identified at birth through the chromosome screening of 40,000 consecutive newborns between 1964 and 1974. In all three nonmosaic groups, reading skills were impaired and intelligence quotients were on average reduced more than 20 points relative to controls. The 47,XXX women demonstrated greatest overall impairment, including reduced scores on tests of conceptualization and problem solving. 45,X women demonstrated impairment in spatial thinking skills, and 47,XXY men in verbal processing skills. No reduced scores were found in the female mosaic group. Marked variability in scores was seen in all groups; some propositi have been unable to hold any job, whereas others have completed college and are professionally employed.

Molecular evidence for the independent origin of extra-ovarian papillary serous tumors of low malignant potential.

BACKGROUND: Molecular data suggest that peritoneal tumors in women with advanced-stage ovarian papillary serous adenocarcinoma are monoclonal in origin. Whether the same is true for ovarian tumors of low malignant potential is not known. We compared peritoneal and ovarian tumors from women with advanced-stage ovarian papillary serous tumors of low malignant potential to determine whether the peritoneal tumors arose from the same clone as the ovarian tumors. METHODS: We studied the clonality of 73 peritoneal and ovarian tumors from 18 women with advanced-stage ovarian papillary serous tumors of low malignant potential. Formalin-fixed, paraffin-embedded tumors and representative normal tissues were sectioned and stained with hematoxylin-eosin, representative sections from separate tumors were manually microdissected, genomic DNA was extracted from the microdissected tumors, and the polymerase chain reaction was used to amplify a CAG polymorphic site in the human androgen receptor locus on the X chromosome to determine the inactivation pattern of the X chromosome and the clonality of the tumors. RESULTS: The pattern of X-chromosome inactivation could be determined from the tumors of 13 of 18 patients. Of the 13 patients, seven (54%) had nonrandom inactivation of the X chromosome, and six of the seven had different inactivation patterns in the peritoneal and ovarian tumors. Three of these patients also had different patterns of nonrandom X-chromosome inactivation in tumors from each ovary. The remaining six patients had random patterns of X-chromosome inactivation in the peritoneal and ovarian tumors. CONCLUSIONS: Our data suggest that peritoneal and ovarian tumors of low malignant potential arise independently.

47,XXX in an adolescent with premature ovarian failure and autoimmune disease.

BACKGROUND: Premature ovarian failure (POF) may be idiopathic or may be associated with genetic or autoimmune disorders. The 47,XXX karyotype has been associated with POF and other genitourinary anomalies. CASE: A 17-year-old woman with a history of immune thrombocytopenic purpura was referred to the adolescent medicine clinic for evaluation of oligomenorrhea with secondary amenorrhea. Evaluation revealed hypergonadotrophic premature ovarian failure, a positive antinuclear antibody, and the 47,XXX karyotype. She has since developed a positive anti-cardiolipin antibody but does not meet diagnostic criteria for systemic lupus erythematosis. CONCLUSION: The presence of known autoimmune disease in a woman with POF should not dissuade the clinician from evaluating for a potential genetic cause.

Maternal folate polymorphisms and the etiology of human nondisjunction.

Attempts to identify genetic contributors to human meiotic nondisjunction have met with little, if any, success. Thus, recent reports linking Down syndrome to maternal polymorphisms at either of two folate metabolism enzymes, methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR), have generated considerable interest. In the present report, we asked whether variation at MTHFR (677C-->T) or MTRR (66A-->G) might be associated with human trisomies other than trisomy 21. We analyzed maternal polymorphisms at MTHFR and MTRR in 93 cases of sex-chromosome trisomy, 44 cases of trisomy 18, and 158 cases of autosomal trisomies 2, 7, 10, 13, 14, 15, 16, 18, or 22, and compared the distributions of genotypes to those of control populations. We observed a significant increase in the MTHFR polymorphism in mothers of trisomy 18 conceptuses but were unable to identify any other significant associations. Overall, our observations suggest that, at least for the sex chromosomes and for a combined set of autosomal trisomies, polymorphisms in the folate pathway are not a significant contributor to human meiotic nondisjunction.

Prenatal diagnosis of two rare de novo structural aberrations of the Y chromosome: cytogenetic and molecular analysis.

Two rare de novo structural aberrations of the Y chromosome were detected during routine prenatal diagnosis: a satellited non-fluorescent Y chromosome (Yqs), the first de novo Yqs to be reported in a fetus, and a terminal deletion of the Y chromosome long arm del(Y)(q11). In both cases detailed cytogenetic and molecular analyses were undertaken. In the case of the Yqs it was demonstrated by fluorescence in situ hybridization (FISH) that the satellites were derived from chromosome 15. In the case of the del(Yq), it was shown with molecular analysis by polymerase chain reaction (PCR) amplification of sequence-tagged sites (STS-PCR) that the deleted portion of the long arm of chromosome Y included the azoospermia factor loci, AZFb and AZFc. The clinical significance of these findings is discussed.

Y-chromosomal microdeletions among infertile Finnish men.

BACKGROUND: Microdeletions in the Y-chromosome are known to cause a significant proportion of azoo- and oligozoospermia in men. The reported frequency of deletions varies greatly between the studies. Probable reasons for this variation are different selection criteria and number of patients included, and possibly also methodological aspects, whereas the contribution of environmental and genetic factors is not known. The aim of this study was to determine the incidence of Y-chromosome microdeletions among infertile Finnish men. METHODS: Two hundred and one men showing azoospermia (n=68) or severe oligozoospermia (n=133) were included. Multiplex polymerase chain reaction method was used to amplify specific sequence tagged sites (STS) along the Y chromosome. RESULTS: Microdeletions were observed in 18 men (9%), of whom four were azoospermic and 14 oligozoospermic. CONCLUSIONS: The incidence of Y-deletions in the study population of infertile Finnish men falls within the range published in other countries.

Histone variant macroH2A contains two distinct macrochromatin domains capable of directing macroH2A to the inactive X chromosome.

Chromatin on the inactive X chromosome (Xi) of female mammals is enriched for the histone variant macroH2A that can be detected at interphase as a distinct nuclear structure referred to as a macro chromatin body (MCB). Green fluorescent protein-tagged and Myc epitope-tagged macroH2A readily form an MCB in the nuclei of transfected female, but not male, cells. Using targeted disruptions, we have identified two macrochromatin domains within macroH2A that are independently capable of MCB formation and association with the Xi. Complete removal of the non-histone C-terminal tail does not reduce the efficiency of association of the variant histone domain of macroH2A with the Xi, indicating that the histone portion alone can target the Xi. The non-histone domain by itself is incapable of MCB formation. However, when directed to the nucleosome by fusion to core histone H2A or H2B, the non-histone tail forms an MCB that appears identical to that of the endogenous protein. Mutagenesis of the non-histone portion of macroH2A localized the region required for MCB formation and targeting to the Xi to an approximately 190 amino acid region.

Recent advances in hereditary spastic paraplegia.

The hereditary spastic paraplegias are a group of rare disorders that are characterized by great clinical and genetic heterogeneity. There has been an exponential increase in the number of HSP loci mapped in recent years, with nine out of the 17 loci reported during the past 2 years. Eight loci have now been identified for the autosomal-dominant form, and seven of these are associated with pure HSP. Spastic paraplegia-4 remains the most frequent locus, and is usually associated with a pure phenotype. Although the corresponding spastin gene was only recently identified, over 50 mutations have been described to date, which renders molecular diagnosis difficult. Five loci are known for autosomal-recessive HSP, and four of these are associated with complex forms, all with different phenotypes. Two genes have been identified: paraplegin and sacsin. Finally, three loci have been identified in X-linked HSP, two of which are complex forms. The genes that encode L1 and PLP were the first to be identified in HSP disorders. Surprisingly, the five genes encode proteins of different families, making understanding and diagnosis of HSP even more difficult. The discovery of new genes should hopefully help to clarify the pathophysiology of these disorders.

Esterilidad masculina y microdeleciones en el cromosoma Y / Male sterility and Y-chromosome microdeletions

No disponible

Identification and characterization of KLHL4, a novel human homologue of the Drosophila Kelch gene that maps within the X-linked cleft palate and Ankyloglossia (CPX) critical region.

X-linked cleft palate (CPX) is a rare nonsyndromic form of orofacial clefting that is, unlike more common forms, inherited as a highly penetrant Mendelian trait. Linkage studies using a large Icelandic kindred localized the gene to Xq21.3, and a physical map defining a 2.0-Mb candidate region was subsequently constructed. Genomic sequence is now available for much of the critical region and has been surveyed for potential transcriptional units. Through this analysis, we have identified a novel human homologue of Kelch, KLHL4. The transcript represents a mRNA of approximately 3.6 kb and encodes a protein of 718 amino acids. Protein domain analysis reveals six tandem repeats (Kelch repeats) at the C-terminus and a POZ/BTB protein-binding domain toward the N-terminus, characteristic of Drosophila Kelch and other family members. KLHL4 consists of 11 exons spanning a genomic interval of approximately 150 kb. From EST sequences and RT-PCR analysis, there is evidence for the use of alternative 3' UTRs. The mRNA is expressed in a range of fetal tissues including tongue, palate, and mandible. Mutational analysis in affected CPX patients revealed one sequence alteration that was most likely to be a silent polymorphism.

A family with X-linked dystonia-deafness syndrome with a novel mutation of the DDP gene.

BACKGROUND: X-linked dystonia-deafness syndrome (DDS) is characterized by early-onset deafness followed by progressive dystonia in adulthood. Only 4 families with the syndrome have been reported, and all were white. OBJECTIVE: To describe the first nonwhite family with X-linked DDS, involving 5 affected males in 4 generations. RESULTS: Clinical features of the family members, who were Japanese, were mostly consistent with reports of DDS in whites except for a lack of visual disturbances. Whereas microdeletions in the deafness-dystonia peptide (DDP) gene were found in 2 white DDS families, our patients showed a novel mutation (arg80ter) in exon 2 of the DDP gene. CONCLUSION: The existence of a DDS family of Japanese origin with a new kind of mutation in the DDP gene provides additional evidence that the DDP gene is a causative gene for X-linked DDS.

Cytogenetic and molecular characterization of two isodicentric Y chromosomes.

We report the results of detailed molecular-cytogenetic studies of two isodicentric Y [idic(Y)] chromosomes identified in patients with complex mosaic karyotypes. We used fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) to determine the structure and genetic content of the abnormal chromosomes. In the first patient, classical cytogenetics and FISH analysis with Y chromosome-specific probes showed in peripheral blood lymphocytes a karyotype with 4 cell lines: 45,X[128]/46,X,+idic(Y)(p11.32)[65]/47,XY,+idic(Y)(p11.32)[2]/47,X,+2idic(Y)(p11.32)[1]. No Y chromosome material was found in the removed gonads. For precise characterization of the Yp breakpoint, FISH and fiberFISH analysis, using a telomeric probe and a panel of cosmid probes from the pseudoautosomal region PAR1, was performed. The results showed that the breakpoint maps approximately 1,000 Kb from Ypter. The second idic(Y) chromosome was found in a boy with mild mental retardation, craniofacial anomalies, and the karyotype in lymphocytes 47,X,+idic(Y)(q11.23),+i(Y)(p10)[77]/46,X,+i(Y)(p10)[23]. To our knowledge, such an association has not been previously described. FISH and PCR analysis indicated the presence of at least two copies of the SRY gene in all analyzed cells. Using 17 PCR primers, the Yq breakpoint was shown to map between sY123 (DYS214) and sY121 (DYS212) loci in interval 5O in AZFb region. Possible mechanisms of formation of abnormal Y chromosomes and karyotype-phenotype correlations are discussed.

Loss of the Y chromosomal PAR2-region in four familial cases of satellited Y chromosomes (Yqs).

Applying fluorescence in-situ hybridization (FISH) of various Y chromosomal DNA probes to four familial cases of human Yqs, it was possible to demonstrate that the formation of Yqs must have arisen from a reciprocal translocation involving the short arm of an acrocentric autosome and the heterochromatin of the long arm of the Y chromosome (Yqh). Breakpoints map within Yqh and the proximal short arm of an acrocentric autosome resulting in the gain of a nucleolus organizer region (NOR) including the telomere repeat (TTAGGG)n combined with the loss of the pseudoautosomal region 2 (PAR2) at the long arm of the recipient Y chromosome. In no case could the reciprocal product of an acrocentric autosome with loss of the NOR and gain of PAR2 be detected. Using the 15p-specific classical satellite-III probe D15Z1 in two of the four Yqs probands presented here, it could be shown that the satellited material originated from the short arm of chromosome 15. In contrast to the loss of PAR2 in Yqs chromosomes, another Y chromosomal variant (Yqh-) showing deletion of long-arm heterochromatin in Yq12 has retained PAR2 referring to an interstitial deletion of Yq heterochromatin in such deleted Y chromosomes.

Gene-environment interplay in oppositional defiant and conduct disorder.

Oppositional defiant and conduct disorder is a disturbance in behavior that is characterized by aggressive and antisocial acts. At present, genetic research on conduct disorder has raised more questions than it has answered, and basic questions such as the heritability of childhood antisocial behavior cannot yet be answered with certainty. Current research, however, has consistently highlighted the importance of gene-environment interplay in antisocial behavior.

A case of ambiguous genitalia presenting with a 45,X/46,Xr(Y)(p11.2;q11.23)/47,X,idic(Y)(p11.2),idic(Y)(p11.2) karyotype.

An infant with ambiguous genitalia was found to have a karyotype 45,X/46,X,r(Y)(p11.2;q11.23)/47,X,idic(Y)(p11.2),idic(Y)(p11.2) using G-banding, C-banding and FISH. Examination of the genitalia revealed a phallus measuring 1.5 cm in length and 0.5 cm wide with perineal orifice. Subtle phenotypic features consistent with Turner syndrome were not present. Genital ultrasonography revealed the presence of an infantile uterus. Endoscopy of the vagina, uterus and cervix appeared normal.

Is routine karyotyping necessary in the evaluation of hypospadias and cryptorchidism?

PURPOSE: The incidence of intersex states has been reported to be 27% to 100% in patients with hypospadias and cryptorchidism, and routinely determining karyotypes has been recommended. This incidence seems much higher than in our experience. We reviewed the records of patients with hypospadias and/or chordee plus cryptorchidism as well as those referred with ambiguous genitalia to determine whether these findings were associated with a high incidence of chromosomal abnormalities and whether they warrant routine karyotype screening. MATERIALS AND METHODS: We reviewed the records of patients with undescended testis plus hypospadias and/or chordee, and those with ambiguous genitalia who presented between 1986 and 1999. Patients without karyotype determination, and those with iatrogenic cryptorchidism, retractile testes, congenital adrenal hyperplasia or female-appearing external genitalia were excluded from study. Meatus and testis locations at surgery, and associated Müllerian structures and medical conditions were documented. Fisher's exact test was done to determine statistical significance. RESULTS: Of the 113 patients whose records matched study inclusion criteria only 48 had complete anatomical, karyotypic, pathological and radiographic information available. Eight patients (16.7%) had chromosomal abnormalities, including 2 (4.2%) with karyotypic intersex disorder and 6 (12.5%) with autosomal chromosomal abnormalities. There were persistent Müllerian structures in 2 patients (4.2%) with a normal 46 XY karyotype. As described by a staff pediatric urologist, 20 patients (41.7%) had ambiguous genitalia and 8 of the 48 (16.7%) had nonpalpable cryptorchidism. Ambiguous genitalia were associated with chromosomal abnormalities, in 4 of the 20 cases, including 2 karyotypic intersex cases. Only 3 patients with ambiguous genitalia had nonpalpable gonads and 1 with karyotypic intersex disorder had a nonpalpable gonad that involved the testicular elements only. The incidence of autosomal chromosomal abnormalities was not significant (2-tailed Fisher's exact test p <==0.05) and the incidence of karyotypic (autosomal or sex) abnormalities was not significant compared with hypospadias (p = 0.3), genital ambiguity (p = 0.7) or cryptorchidism (p = 0.69), including nonpalpable testis (p = 1). When patients had karyotypic abnormalities, they were more likely to have proximal hypospadias (57.2%), palpable cryptorchidism (62.5%) and ambiguous genitalia (50%). CONCLUSIONS: Most patients who present for the evaluation of hypospadias, chordee and undescended testis have a normal karyotype. Routine karyotype investigation of all patients with hypospadias, chordee and cryptorchidism does not seem warranted. If karyotypic intersex abnormalities are identified, those patients are more likely to have ambiguous genitalia, especially those with perineal hypospadias and cryptorchidism.

MRI and proton spectroscopy in Lowe syndrome.

The oculocerebrorenal syndrome of Lowe (OCRL) is an X-linked disorder characterized by major abnormalities of eyes, nervous system, and kidneys. We report two patients with typical intracranial lesions on MRI. The proton spectroscopy study of the periventricular white matter showed a moderate elevation of the signal at 3.56 ppm in the patient with cystic lesions. This resonance is usually assigned to myo-inositol and interpreted as a glial marker. In our patient it could also represent a true accumulation inside the cysts of phosphatidylinositol 4,5-biphosphate which is not degraded in patients with Lowe syndrome.