Chromosome 16 abnormalities in embryos and in sperm from a male with a fragile site at 16q22.1.

Two fragile sites, FRA16B and FRA16C, are located in the chromosome band 16q22.1. Neither of them is associated with any specific clinical condition. We report the development and outcome of a clinically applied PGD cycle in a couple who had difficulty in achieving pregnancy. The woman was a carrier of a balanced reciprocal translocation, t(11;22)(q23;q11.2), and the man presented high expression of the fragile site 16q22.1 (FRA16B/C) in peripheral blood lymphocytes. Gains and losses of chromosome 16 fragments were detected in sperm and embryos. To our knowledge, this is the first documented case suggesting a link between FRA16B/C and chromosome 16 abnormalities in embryos and sperm from a carrier.

First successful double-factor PGD for Lynch syndrome: monogenic analysis and comprehensive aneuploidy screening.

Preimplantation genetic diagnosis (PGD) has been applied worldwide for a great variety of single-gene disorders over the last 20 years. The aim of this work was to perform a double-factor preimplantation genetic diagnosis (DF-PGD) protocol in a family at risk for Lynch syndrome. The family underwent a DF-PGD approach in which two blastomeres from each cleavage-stage embryo were biopsied and used for monogenic and comprehensive cytogenetic analysis, respectively. Fourteen embryos were biopsied for the monogenic disease and after multiple displacement amplification (MDA), 12 embryos were diagnosed; 5 being non-affected and 7 affected by the disease. Thirteen were biopsied to perform the aneuploidy screening by short-comparative genomic hybridization (CGH). The improved DF-PGD approach permitted the selection of not only healthy but also euploid embryos for transfer. This has been the first time a double analysis of embryos has been performed in a family affected by Lynch syndrome, resulting in the birth of two healthy children. The protocol described in this work offers a reliable alternative for single-gene disorder assessment together with a comprehensive aneuploidy screening of the embryos that may increase the chances of pregnancy and birth of transferred embryos.

El banco de semen y la supervivencia espermática en un programa de reproducción asistida / The bank of semen and sperm survival in an assisted reproduction program

Objetivo: Analizar el efecto de las condiciones de almacenamiento de semen congelado sobre la fragmentación del ADN espermático, los parámetros seminales pre y post congelación, la recuperación espermática tras selección-capacitación de los donantes de semen (DS) utilizados en inseminación intrauterina y los resultados de gestación, teniendo en cuenta los efectos del tiempo de congelación y la ubicación de los viales en el contenedor criogénico. Material y Métodos: Se valoraron muestras de 17 (DS) criopreservadas entre el 2003-2008 y que fueron utilizadas en 77 procesos de inseminación intrauterina. El estudio de la fragmentación espermática se realizó mediante el método SCD (Sperm Cromatin Dispersion) (Halosperm ®, Indas). Se analizó la pérdida relativa de la motilidad progresiva post descongelación y post selección espermática (centrifugación de gradientes).También se evaluó la tasa de gestación/ciclo. Todos los parámetros se analizaron teniendo en cuenta el tiempo de almacenamiento al descongelar (≥ 3 o < 3 años) y la ubicación relativa de almacenamiento dentro del contenedor (1=más superficial, 11=más profundo). Resultados: El IFS (Indice de Fragmentación Espermático) fue en los 17 DS estudiados de 14,47±1,28. Cuando analizamos el IFS según el tiempo de almacenamiento ≥ 3 o < 3 años los resultados fueron similares (13,50±2,63 versus 15,85±2,66%) p < 0,39. Cuando el tiempo de almacenamiento fue superior a 3 años la motilidad progresiva (a+b) post descongelación fue menor que los almacenados menos de 3 años (3,7± 2,6 versus 41,9±2,4%) p<0,05. El mismo efecto se observó post selección espermática (36,9±2,9 versus 46,8±2,9%) p < 0,019. La tasa global de gestación/ciclo fue de 11,16%. No se observó diferencia significativa del IFS entre el nivel de más superficial a más profundo del contenedor criogénico (15,89±2,33 versus 12,88±0,64%) p < 0,25 ni tampoco de los parámetros seminales de motilidad progresiva (33,19±3,97 versus 38,33±4,72%) p < 0,40. Conclusiones: El índice de fragmentación espermático (IFS) no se modificó con el tiempo de criopreservación ni por el nivel de ubicación de las muestras en el contenedor criogénico. La motilidad progresiva (a+b) post descongelación y post selección espermática empeoró con el tiempo de almacenamiento pero no se vio influida por el nivel de almacenamiento (AU)

Effect of the conditions of storage of semen frozen on the fragmentation of the DNA and the pre and post freezing seminal parameters, as well as spermatic selection by density gradient semen donors (SD) used for intrauterine insemination; also to analyse pregnancy outcomes, and the effects of freezing time and vial location inside the cryogenic container. Material and Methods: Samples cryopreserved between 2003 and 2008 from 17 SD and used in 70 intrauterine insemination, were evaluated. The sperm DNA fragmentation was carried out of the SCD (Sperm Cromatin Dispersion) method ( Halosperm® Indas). Post-thaw and postsperm selection relative loss of progressive mobility was analysed (gradient centrifugation). Also the pregnancy/cycle rate was assessed. All parameters were analysed considering the storage time at thawing (≥ 3 or < 3 years), and their relative location within the container (1 = most superficial, 11 = deepest). Results: The time of criopreservation was 978±79 days (media±EEM). The IFS was 14.47±1.28 in 17 studied DS. When we analyze the IFS according to the time of storage (≥ 3 or <3) years the results were similar (13.50±2.63 versus 15.85±2.66 %) p < 0.39. When the time of storage was superior to 3 years the progressive motility (a+b) post thawed was minor, that the stored less than 3 years (34.7 ± 2.6 versus 41.9±2.4 %) p < 0.05. The same effect observed post spermatic selection (36.9±2.9 versus 46.8±2.9 %) p< 0.019. The global rate of gestation / cycle was 11.16 %. Was not observed significant difference of the IFS between the level of more superficial to deeper of the cryogenic container (15.89±2.33 versus 12.88±0.64 %) p <0.25 not neither of the seminal parameters of progressive motility (33.19±3.97 versus 38.33±4.72 %) p < 0.40. Conclusions: The spermatic index of fragmentation (IFS) they were not modified by the time of cryopreservation not by the level of location of the samples in the cryogenic container. The progressive motility (a+b) post thawing and post spermatic selection deteriorated with the time of storage but not see influenced by the level of storage (AU)

Acrocentric chromosome disomy is increased in spermatozoa from fathers of Turner syndrome patients.

The aim of the present study was to investigate whether there was an increase of aneuploidy in the sperm from fathers of Turner syndrome patients of paternal origin who, in a previous study, showed an elevated incidence of XY meiotic nondisjunction. Sperm disomy frequencies for chromosomes 4, 13, 18, 21 and 22 were assessed by fluorescence in situ hybridisation in four of these individuals. As a group, the Turner syndrome fathers showed a general increase in disomy frequencies for chromosomes 13, 21 and 22, with a statistically significant increase in disomy frequencies for chromosomes 13 and 22 in one of the fathers and for chromosome 21 in two of them. Data from a previous work carried out by us in two fathers of Down syndrome patients of paternal origin also revealed increased sperm disomy frequencies for chromosomes 13, 21 and 22. Pooled as one group, these six fathers of aneuploid offspring of paternal origin had a statistically significant increase in the frequency of nondisjunction for these chromosomes with respect to control individuals. Our findings indicate that there may be an association between fathering aneuploid offspring and increased frequencies of aneuploid spermatozoa. Such increases do not seem to be restricted to the chromosome pair responsible for the aneuploid offspring. Acrocentric chromosomes and other chromosome pairs that usually show only one chiasma during meiosis seem to be more susceptible to malsegregation.

Linear increase of diploidy in human sperm with age: a four-colour FISH study.

The aim of this study was to determine if donor age is associated with an increased incidence of diploidy and of disomy for the sex chromosomes and for chromosomes 6 and 21. We used simultaneous fluorescence in situ hybridisation (FISH) for chromosomes 6, 21, X and Y in sperm from 18 healthy donors, aged 24-74 years (mean 48.8 years). A total of 194 024 sperm were analysed, with a minimum of 10 000 sperm scored for each donor. Our results indicate a significant increase of the level of diploidy (P=0.002), and a marginal significance of total sex chromosome disomy (P=0.055) with age. No increase was observed for disomies XX, YY, XY, 21 or 6. The percentages of increase for disomy and for diploidy ranged from 0.3 to 17% for each 10-year period. Chromosomes 6 and 21 did not segregate preferentially with the X or Y chromosomes. Our findings show a linear trend association between age and diploidy in human males.

Paternal sex chromosome aneuploidy as a possible origin of Turner syndrome in monozygotic twins: case report.

The meiotic or mitotic origin of most cases of Turner syndrome remains unknown, due to the difficulty in detecting hidden mosaicisms and to the lack of meiotic segregation studies. We have had the opportunity to study one pair of monozygotic twins concordant for Turner syndrome of paternal origin. The paternal origin of the single X chromosome was determined by polymerase chain reaction (PCR) amplification. No mosaicism was detected for the X or Y chromosome. In this case, a meiotic error during gametogenesis would be a likely origin of X monosomy. To determine if meiotic errors are more frequent in the father of these monozygotic twins concordant for Turner syndrome of paternal origin, molecular studies in spermatozoa were conducted to analyse sex chromosome numerical abnormalities. A total of 12520 sperm nuclei from the twins' father and 85338 sperm nuclei from eight normal donors were analysed using three-colour fluorescent in-situ hybridization. There were significant differences between the twins' father and control donors for XY disomy (0.22 versus 0.11%, P < 0.001) and total sex chromosome disomy (0.38 versus 0.21%, P < 0.001). These results could indicate an increased tendency to meiotic sex chromosome non-disjunction in the father of the Turner twins.

PCR protocol to detect parental origin and hidden mosaicism inSex chromosome aneuploidies.

In this study, we report an accurate method to determine the parental origin of sex chromosome aneuploidies or polyploidies and to detect low percentage mosaicisms. We have amplified by polymerase chain reaction (PCR) five polymorphic markers along the X chromosome (DXS1283E, DYS II, DMD49, AR and DXS52) and three markers along the Y chromosome (SRY, DYZ3 and DYZ1). False-negative results were discarded by the simultaneous amplification of Y markers and of internal controls. We have applied this protocol to a series of 14 Turner syndrome patients with a 45,X karyotype. We have detected sex chromosome mosaicisms in two patients. The parental origin of the syndrome has been determined in the other 12 patients.

Analysis of sex chromosome aneuploidy in sperm from fathers of Turner syndrome patients.

Numerical sex chromosome abnormalities were analyzed in sperm from four fathers of Turner syndrome patients of paternal origin to determine whether there was an increased frequency of sex chromosome aneuploidy and to elucidate whether meiotic malsegregation mechanisms could be involved in the origin of Turner syndrome. Determination of the parental origin of the single X chromosome (maternal in all four cases) and exclusion of X and Y mosaicism were carried out by polymerase chain reaction amplification of five X chromosome polymorphisms and three Y chromosome segments. A total of 45,299 sperm nuclei from Turner fathers and 85,423 sperm nuclei from eight control donors was analyzed by three-color fluorescence in situ hybridization. The four patients showed a significant increase in the percentages of XY sperm (mean 0.22%; range 0.20% to 0.22%) compared with control donors (mean 0.11%; range 0.06% to 0.18%). These results suggest that the four individuals have an increased frequency of nondisjunctional errors in meiosis I, resulting in the production of an increased proportion of XY spermatozoa and of sperm lacking a sex chromosome.

Sperm chromosome analysis in the father of a child with a de-novo reciprocal translocation t(11;15)(q12;q22) by G-banding and fluorescence in-situ hybridization.

Analysis of sperm chromosomes by G-banding and two-colour fluorescence in-situ hybridization (FISH) was carried out in the father of a child with a de-novo reciprocal translocation t(11;15)(q12;q22). Sperm chromosome complements were obtained after in-vitro fusion of zona-free hamster oocytes and donor spermatozoa. A total of 112 sperm complements was first analysed by G-banding. The frequency of structural chromosome aberrations (9.8%) and the conservative frequency of aneuploidy (0.0%) were not significantly different from those obtained in our control donors. The proportions of X-bearing (53.2%) and Y-bearing (46.8%) spermatozoa were not significantly different from the expected 1:1 ratio. A total of 313 sperm complements was analysed by two-colour FISH. The frequency of structural abnormalities for chromosomes 11 and 15 was 3.2 and 0.3% respectively. The frequency of rearrangements for chromosome 11 was statistically significant when compared with control donors (0.4%) (P < 0.0001). No spermatozoa with the t(11;15)(q12;q22) translocation were observed, showing no evidence for a germ-cell mosaicism. These results suggest that the de-novo involvement of chromosome 11 in a structural rearrangement is not random, and that in this patient an increased risk of de-novo structural chromosome abnormalities in further offspring does exist.

Cytogenetic analysis of spermatozoa in the father of a child with a de-novo reciprocal translocation t(7;9) (q22;p23).

Analysis of sperm chromosomes was carried out in the father of a child with a de-novo reciprocal translocation t(7;9) (q22;p23) by G-banding and chromosome painting. Sperm metaphases were obtained using the zona-free hamster oocyte-human sperm fusion technique. A total of 138 complements were sequentially analysed by G-banding and fluorescence in-situ hybridization (FISH). The frequency of spermatozoa with structural chromosome abnormalities (5.1%) and the estimated conservative aneuploidy (1.4%) were within the range obtained in our control donors (6.9 and 4%). The sex ratio (45.3% X versus 54.7% Y) was not significantly different from the theoretical 1:1. A total of 309 sperm complements was analysed by FISH, 138 sequentially analysed by G-banding-FISH and another 171 analysed by FISH only. The frequencies of structural chromosome abnormalities for chromosomes 7 and 9 (0.6 and 0% respectively) were not significantly different from those obtained in our control donors (0.6 and 0.8%). No spermatozoa with the t(7;9) (q22;p23) were observed, showing no evidence for a germ-cell mosaicism. A statistically significant, positive association between sperm breakpoints and fragile sites (P = 0.0225) was observed. However, the coincidence between fragile sites and sperm breaks (80%) was not significantly different from that obtained in our control donors (79.2%). These results suggest that in this case the risk of structural chromosome abnormalities in further offspring is not increased, although an association between fragile sites and sperm chromosome breaks in the father does exist.

Chromosome segregation in a man heterozygous for a pericentric inversion, inv(9)(p11q13), analyzed by using sperm karyotyping and two-color fluorescence in situ hybridization on sperm nuclei.

Analysis of sperm karyotypes and two-color fluorescent in situ hybridization (FISH) on sperm nuclei were carried out in a man heterozygous for the pericentric inversion inv(9)(p11q13). Sperm chromosome complements were obtained after in vitro fusion of zona-free hamster oocytes and donor sperm. A total of 314 sperm complements was analyzed: 153 (48.7%) carried the inverted chromosome 9 and 161 (51.3%) carried the normal one. None of the sperm complements contained a recombinant chromosome 9, suggesting that no chiasmata were formed in the heterochromatic region. The frequency of structural chromosome aberrations unrelated to the inversion (8.3%) and the frequency of conservative aneuploidy (3.2%) were within the limits observed in our control donors. The proportions of X-bearing (47.3%) and Y-bearing sperm (52.7%) were not significantly different from the expected 1:1 ratio. The percentage of disomy for chromosome 21 was analyzed by two-color FISH in 10336 sperm nuclei. The disomy rate for chromosome 21 (0.30%) was not significantly different from that found in our controls. These results suggest that the risk for this man of producing chromosomally abnormal offspring or spontaneous abortions was not increased, and do not support the existence of an interchromosomal effect for chromosome 21.

Analysis of human sperm-derived pronuclei by three-colour fluorescent in-situ hybridization.

We describe a modification of the human sperm-zona-free hamster egg fusion method that permits the study of aneuploidy in sperm-derived pronuclei by multicolour fluorescent in-situ hybridization (FISH). Zona-free hamster eggs and human spermatozoa were fused and cultured for 15 h in the presence of colcemid (1 microg/ml of medium) to obtain hamster oocytes arrested at metaphase II and human spermatozoa at the pronuclear stage. By applying a whole human genomic DNA probe we confirmed that 100% of pronuclei tested (372/372) were of human origin. One-colour fluorescent in-situ hybridization using a centromeric 18 probe was applied to 919 pronuclei with different dithiothreitol (DTT) pretreatments: 50 mM (10 min) or 25 mM (20 and 25 min). The highest hybridization efficiency was obtained with treatment with 25 mM DTT for 20 min (90.3%). Sex chromosome aneuploidy was analysed by three-colour FISH in a total of 2596 pronuclei from a normal donor. Hybridization efficiency was 98.6%. The disomy rates for X, Y and XY chromosomes (0.11, 0.04 and 0.08% respectively) were similar to data reported for sperm nuclei by three-colour FISH and to those obtained in sperm chromosomes. These results suggest that selection of potentially fertile spermatozoa (spermatozoa able to fertilize zona-free hamster eggs and produce a pronucleus) does not imply chromosomal selection.

Sequential G-banding FISH on human sperm chromosomes.

A method that allows the performance of double-colour chromosome painting (FISH) on previously G-banded human sperm metaphases has been developed. Sperm chromosomes were obtained by using the fusion technique between zona-free hamster oocytes and human spermatozoa. Single- and double-colour chromosome painting was performed using DNA libraries specific for chromosomes X, Y and 21 on either unstained or G-banded preparations. The hybridization efficiency was very high (98%). The sequential staining technique is very useful for analyses of structural (stable) and numerical chromosome aberrations in human sperm and thus can increase the efficiency of the human sperm-hamster oocytes fusion system to assess the risk to human germ cells as a result of endogenous and exogenous factors.