Biomedical subjects

N Bouayed Abdelmoula

Publications and source records attributed to N Bouayed Abdelmoula.

5 recordsLinked to original sources

PubMedDate not supplied

Turner syndrome female with a small ring X chromosome lacking the XIST, an unexpectedly mild phenotype and an atypical association with alopecia universalis.

Rearranged X chromosome in Turner syndrome (TS) are generally well tolerated but in cases of ring X chromosomes and of X/autosome translocations the incidence of mental retardation and other congenital abnormalities can be significantly higher. These abnormal phenotypes can be ascribed to failed or partial X inactivation. Here, we report a 10-year-old female who was referred for a cytogenetic analysis because she developed an alopecia universalis. The patient, of normal intelligence, had been found to have traits of TS, especially short stature. A first cytogenetic analysis showed a no mosaic 45,X karyotype. Since, the risk of developing gonadoblastoma in TS patients with mosaicism for a Y derivative chromosome and because association of alopecia universalis and TS is uncommon, fluorescence in situ hybridization (FISH) was performed to search for a second cell population. Our patient was found to have a mosaic 45,X/46,X,+r. FISH analysis using sex chromosome probes permitted us to identify the very small marker as a ring X chromosome, detected in 90% of cells. The ring appeared to be formed almost totally of alphoid sequences with breakpoints in the juxtacentromeric region. The r(X) does not include the XIST locus and may, therefore, not be subject to X-inactivation. Unexpectedly mild phenotype in our patient and its association with alopecia universalis will be discussed.

Abnormalities, Multiple↗

PubMedDate not supplied

Evaluation of DAZ microdeletions in 34 infertile men.

Microdeletions in Yq11 are a common molecular cause of spermatogenic failure in men and are recurrently detected in about 10-15% of idiopathic azoospermia and severe oligozoospermia. Screening for AZF microdeletions is often performed by multiplex PCR. AZFc deletions, involving the DAZ gene, form the majority of these deletions. The aim of this study was to evaluate in a group of 34 Tunisian infertile patients (16 oligozoospermic and 18 azoospermic men) the prevalence of DAZ microdeletions using a rapid molecular strategy: the PCR-DGGE method based on the high degree of homology between the DAZ gene and its autosomally equivalent DAZLA gene. DAZ microdeletions were detected in 8.8% of patients. The three deleted patients have a 46, XY karyotype. Two of them were azoospermic and the other had an extreme oligo-asthenoteratozoospermia with a predominant abnormality: small round head spermatozoa (Y46). Our findings suggest that PCR-DGGE method, for detection of DAZ gene deletion, could be particularly useful as a first step in the diagnosis workup of nonobstructive azoospermia and severe oligozoospermia for three reasons. First, it is a simple and fast system; second, DAZ microdeletions are the most common Y deletions; and third, partial DAZ microdeletions and mosaicism may be recognized by PCR-DGGE while only deletions removing the whole DAZ gene cluster can be detected by STS-PCR [211]. Nevertheless, this procedure has limitations because other deletions of AZFa and AZFb may go undetected. Therefore, molecular investigation by multiplex PCR must be conducted in a second step according to European guidelines for the molecular diagnosis of Y chromosome microdeletions, particularly before ICSI procedures.

Chromosome Deletion↗

PubMedDate not supplied

[Contribution of molecular cytogenetics in the diagnosis of chromosomal abnormalities].

Molecular cytogenetic approaches based on fluorescence in situ hybridization (FISH) with chromosome-specific probes have been increased in recent years. They become a powerful tool for chromosomal diagnosis in prenatal, constitutional and cancers genetic disorders. In fact, various procedures are now available to rapid identification of numerical and structural chromosome aberrations that escape to conventional chromosome banding analysis. Here, contribution of molecular cytogenetic approaches for diagnosis of disease related chromosomal changes are presented and discussed.

Chromosome Aberrations↗

PubMedDate not supplied

[Dicentric Y chromosomes. First part: cytogenetic and molecular aspects].

Dicentric Y chromosomes have been reviewed twice in 1994 by Hsu et al. and in 1995 by Tuck-Muller et al. who showed that dic(Y) are the most common Y structural abnormalities and that their influence on gonadal and somatic development is extremely variable. The prediction of their phenotypic consequences is often difficult because of the variety of genomic sequences concerned by duplications and deletions, because of the variable degrees of mosaicism (cell line 45,X in particular) and at the end, because of identification and analysis technical difficulties of the structure of the rearranged Y chromosome. The clinical specter of this cytogenetic abnormality is rather wide going from almost-normal or infertile males, to females with or without stigmas of Turner syndrome. Middle phenotypes consist of various degrees of genital ambiguities. However, clinical expression seems to be related to the genomic capital of the Y chromosome, mainly the Y genes involved in the control of the process of the determination of gonads (Yp) and spermatogenesis (Yq) as well as control of the growth and the skeletal development (Yp). Here, we report a third comprehensive review of the literature concerning dicentric Y chromosomes reported since 1994. In the light of previous reviews as well as the recent data of the genetic cartography of the Y chromosome, we try, in this first part, to determine characteristics of reported dicentric Y chromosomes as well as their chromosomal mechanics, their mitotic stability and finally their cytogenetic and molecular investigations.

Chromosomes, Human, Y↗

PubMedDate not supplied

[Dicentric Y chromosome].

Dicentric Y chromosomes are the most common Y structural abnormalities and their influence on gonadal and somatic development is extremely variable. Here, we report the third comprehensive review of the literature concerning dicentric Y chromosomes reported since 1994. We find 78 new cases for which molecular studies (PCR or FISH) have been widely applied to investigate SRY (68% of cases), GBY, ZFY, RFS4Y, GCY and different genes at AZF region. For dic(Yq), all cases (n = 20) were mosaic for 45,X and 4 of them were also mosaic for a 46,XY cell line. When breakpoints were available (15/20 cases), they were in Yp11. 50% of cases were phenotypic female and 20% phenotypic male while 20% of cases were reported with gonadal dysgenesis. Gonadal histology was defined in 8 cases but only in one case, gonadal tissu was genetically investigated because of gonadoblastoma. For dic(Yp) (n = 55), mosaicism concerned only 45,X cell line and was found in 50 cases while the remainder five cases were homogeneous. When breakpoints were available, it was at Yq11 in 50 cases and at Yq12 in two cases. 54% of cases were phenotypic female, 26% were phenotypic male and 18% were associated with genitalia ambiguous. SRY was analyzed in 33 cases, sequenced in 9 cases and was muted in only one case. Gonads were histologically explored in 34 cases and genetically investigated in 8 cases. Gonadoblastoma was found in only two cases. Through this review, it seems that phenotype-genotype correlations are still not possible and that homogeneous studies of dic(Y) in more patients using molecular tools for structural characterization of the rearranged Y chromosome and assessment of mosaicism in many organs are necessary to clarify the basis of the phenotypic heterogeneity of dicentric Y chromosomes and then to help phenotypic prediction of such chromosome rearrangement.

Chromosomes, Human, Y↗