In utero hematopoietic stem cell transplantation in canines: exploring the gestational age window of opportunity to maximize engraftment.

OBJECTIVE: In utero hematopoietic stem cell transplantation (IUHSCT) is a promising therapy for a variety of congenital disorders. Our objective was to determine the optimal time in gestation for IUHSCT in a canine model. METHODS: IUHSCT was performed in day 31-50 (term 63) fetal canines with CD34+ cells isolated from paternal bone marrow at doses of 0.09-3.4 × 109 CD34+ cells/kg and T cells (CD3+/CD5+) from paternal blood at 0.11-1.1 × 109 cells/kg. Engraftment was assayed using PCR-based chimerism analysis (SRY gene detection for female recipients, and unique microsatellite loci for both sexes). RESULTS: Microchimerism and chimerism were present in multiple recipients across most gestational ages at transplant. Maximal engraftment was obtained in hematopoietic tissues in transplants performed at 42 days. At extremes of recipient gestational age, minimal to no engraftment was seen. CONCLUSION: Fetal age at the time of IUHSCT plays an important role in achieving engraftment in our canine model.

X-linked adrenoleukodystrophy: ABCD1 de novo mutations and mosaicism.

X-linked adrenoleukodystrophy (X-ALD) is a progressive peroxisomal disorder affecting adrenal glands, testes and myelin stability that is caused by mutations in the ABCD1 (NM_000033) gene. Males with X-ALD may be diagnosed by the demonstration of elevated very long chain fatty acid (VLCFA) levels in plasma. In contrast, only 80% of female carriers have elevated plasma VLCFA; therefore targeted mutation analysis is the most effective means for carrier detection. Amongst 489 X-ALD families tested at Kennedy Krieger Institute, we identified 20 cases in which the ABCD1 mutation was de novo in the index case, indicating that the mutation arose in the maternal germ line and supporting a new mutation rate of at least 4.1% for this group. In addition, we identified 10 cases in which a de novo mutation arose in the mother or the grandmother of the index case. In two of these cases studies indicated that the mothers were low level gonosomal mosaics. In a third case biochemical, molecular and pedigree analysis indicated the mother was a gonadal mosaic. To the best of our knowledge mosaicism has not been previously reported in X-ALD. In addition, we identified one pedigree in which the maternal grandfather was mosaic for the familial ABCD1 mutation. Less than 1% of our patient population had evidence of gonadal or gonosomal mosaicism, suggesting it is a rare occurrence for this gene and its associated disorders. However, the residual maternal risk for having additional ovum carrying the mutant allele identified in an index case that appears to have a de novo mutation is at least 13%.

Prenatal detection of a subtle unbalanced chromosome rearrangement by karyotyping, FISH and array comparative genomic hybridization.

OBJECTIVES: To explore the advantages and limitations of comparative genomic hybridization to BAC arrays (array CGH) for prenatal diagnosis of a fetus with anomalies and a chromosome abnormality. METHODS: We used karyotype analysis, FISH and array CGH to investigate an unbalanced chromosome rearrangement. RESULTS: We report a case of a fetus with ultrasound anomalies at 11 weeks' gestation and an unbalanced chromosome translocation [46,XX,der(13)t(2;13)(p25.1;q32)pat]. Initially, a chromosome 13 deletion was reported from G-banded chromosome analysis and 13q subtelomere FISH. The involvement of chromosome 2 was determined after a balanced translocation was identified in the father, 46,XY,t(2;13)(p25.1;q32). Array CGH confirmed the fetal abnormality as partial trisomy of the short arm chromosome 2 and partial monosomy of the long arm of chromosome 13. The abnormalities identified by ultrasound studies and autopsy appear to be most consistent with 13q deletion syndrome. CONCLUSIONS: Array CGH successfully identified a subtle unbalanced chromosome complement in a fetus with multiple ultrasound anomalies. If array CGH had been performed along with the fetal karyotype, the cryptic partial trisomy 2 could have been identified in a more timely manner to assist in the prenatal counseling of this family.

Clinical consequences of an increasing trend of preferential use of cultured villi for molecular diagnosis by CVS.

OBJECTIVE: To compare the use of uncultured versus cultured villus cells for DNA-based prenatal diagnosis. METHODS: A retrospective review of molecular testing of chorionic villus sampling (CVS) cases from 1988-2007. Method of analysis, gestational age (GA) at CVS and at diagnosis, time from procedure to results, results of maternal contamination studies, and the laboratory employed were abstracted from patient charts. Trends in laboratory practices over time were analyzed. RESULTS: Time from CVS to diagnosis was longer when cultured cells were used. Average GA at diagnosis was 14-6/7 weeks with cultured cells vs 13-0/7 weeks with uncultured villi (p < 0.001). Recently, laboratories are more frequently requiring cultured cells, resulting in significantly greater delays in time to diagnosis and GA at results. CONCLUSIONS: 'Direct' DNA extraction saves 2 weeks from CVS to results. More women are afforded the option of an earlier, safer pregnancy termination if uncultured villi are used for molecular diagnosis. Implementation of standardized DNA extraction protocols and sample-size requirements can optimize the use of uncultured villi for molecular prenatal diagnosis. Increased awareness of the importance of rapid results and the advantages of 'direct' DNA extraction from uncultured villi can lead to improvements that are of clinical significance for patients undergoing early prenatal diagnosis.

Prenatal diagnosis of mosaic trisomy 8q studied by ultrasound, cytogenetics, and array-CGH.

Mosaic trisomy 8, also known as Warkany syndrome, has a well-characterized constellation of phenotypic findings. Partial trisomy 8, including mosaic cases, has also been reported, with outcome and counseling dependent on the chromosomal segment involved and whether accompanied by partial aneuploidy for other chromosomes. We present a case of a fetus mosaic for trisomy of the entire long arm (q) of chromosome 8 without additional chromosomal aberrations. The diagnosis was made by amniocentesis performed following an 18 week sonogram that showed multiple fetal anomalies. Mosaicism for trisomy 8q was confirmed by routine karyotyping and fluorescent in situ hybridization (FISH) analysis. The case proved useful for testing the sensitivity of array comparative genomic hybridization (array-CGH) with respect to segmental trisomy in the presence of chromosomal mosaicism. The phenotype of this fetus, which appears to be the first reported case involving mosaic trisomy 8 for the entire q arm of the chromosome, is described and compared to previously reported cases involving partial trisomy 8q.

X inactivation in triploidy and trisomy: the search for autosomal transfactors that choose the active X.

Only one X chromosome functions in diploid human cells irrespective of the sex of the individual and the number of X chromosomes. Yet, as we show, more than one X is active in the majority of human triploid cells. Therefore, we suggest that (i) the active X is chosen by repression of its XIST locus, (ii) the repressor is encoded by an autosome and is dosage sensitive, and (iii) the extra dose of this key repressor enables the expression of more than one X in triploid cells. Because autosomal trisomies might help locate the putative dosage sensitive trans-acting factor, we looked for two active X chromosomes in such cells. Previously, we reported that females trisomic for 18 different human autosomes had only one active X and a normal inactive X chromosome. Now we report the effect of triplication of the four autosomes not studied previously; data about these rare trisomies - full or partial - were used to identify autosomal regions relevant to the choice of active X. We find that triplication of the entire chromosomes 5 and 11 and parts of chromosomes 1 and 19 is associated with normal patterns of X inactivation, excluding these as candidate regions. However, females with inherited triplications of 1p21.3-q25.3, 1p31 and 19p13.2-q13.33 were not ascertained. Thus, if a single key dose-sensitive gene induces XIST repression, it could reside in one of these locations. Alternatively, more than one dosage-sensitive autosomal locus is required to form the repressor complex.

Microphthalmia with linear skin defects (MLS) syndrome evaluated by prenatal karyotyping, FISH and array comparative genomic hybridization.

OBJECTIVE: To explore the utility of comparative genomic hybridization to BAC arrays (array CGH) for prenatal diagnosis of microphthalmia and linear skin defects syndrome. METHODS: We used karyotype analysis, FISH and array CGH to investigate an X;Y translocation. Replication studies were done on cultured amniocytes and lymphoblasts. RESULTS: We describe a severe case of MLS syndrome that presented prenatally with multiple anomalies including cystic hygroma, microphthalmia, intrauterine growth restriction and a complex congenital heart defect. Cytogenetic analysis of amniocytes revealed an unbalanced de novo translocation between chromosomes X and Y [karyotype 46,X,der(X)t(X;Y)(p22.3;q11.2).ish der(X)(DXZ1+,DMD+,KAL-,STS-,SRY-),22q11.2 (Tuple1 x 2)]. MLS diagnosis was made at birth and the prenatal karyotype was confirmed. Replication studies showed the derivative X chromosome was the inactive X. Array CGH confirmed the X and Y imbalances seen in the karyotype and also showed twelve BACs in the MLS region were deleted as a result of the translocation. FISH with BAC clones verified the array findings and placed the X breakpoint in Xp22.2, resulting in the amended karyotype, 46,X,der(X)t(X;Y)(p22.2;q11.2).ish der(X)(DXZ1+,DMD+,KAL-,STS-,SRY-),22q11.2(Tuple1 x 2) arr cgh Xp22.33p22.2(LLNOYCO3M15D10 -->GS1-590J6)x 1,Yq11.222q23(RP11-20H21-->RP11-79J10)x 1. CONCLUSION: The sensitivity of array CGH was valuable in detecting monosomy of the MLS critical region. Array CGH should be considered for the prenatal diagnosis of this syndrome.

Use of T-cell antibodies for donor dosaging in a canine model of in utero hematopoietic stem cell transplantation.

AIM: Microchimerism following canine in utero hematopoietic stem cell transplantation (IUHSCT) development of T-cell dosing regimens. OBJECTIVE: To investigate the use of anti-T-cell antibodies for cell dosing of the donor graft in a canine model of IUHSCT. STUDY DESIGN: Canine IUHSCT was performed by ultrasound-guided intraperitoneal injection in days 35-38 of fetal canines with CD34(+) cells at doses of 4.5 x 10(8) to 1.3 x 10(9) cells/kg and T cells (CD3(+) CD5(+)) at doses of 8 x 10(6) to 8.8 x 10(8) cells/kg. Postnatal studies included tissue histology and polymerase chain reaction-based chimerism analysis. RESULTS: Term survival was 86-100%. Microchimerism (0-2%) was detected in five of eight recipients in multiple tissues. Histopathology revealed no evidence of graft-versus-host disease (GVHD). CONCLUSION: Canine IUHSCT is a useful model to investigate the role of donor T cells in engraftment and GVHD. IUHSCT at early gestational ages with high doses of donor T cells in the graft yields microchimerism in multiple tissues without GVHD.

Frequency of chromosomal abnormalities in spontaneous abortions derived from intracytoplasmic sperm injection compared with those from in vitro fertilization.

No statistical difference was found for the total aneuploidy rate in the spontaneous abortions between intracytoplasmic sperm injection and IVF groups; however, differences in the distribution of chromosomal abnormalities between the two groups were seen.

Autopsy findings of a 37-year-old man with a complex mosaic karyotype involving del(18p), monosomy 13, and trisomy 20.

We report on the autopsy findings of a 37-year-old man with a complex karyotype (mos46,XY,del(18)(p11.1)[14]/46,XY, -13, del (18)(p11.1), +20[8]/47,XY,del(18)(p11.1), +20[8]). He was known to be blind, non-ambulatory, have severe mental retardation, and a seizure disorder. External physical findings at the time of autopsy included micrognathia, short stubby fingers, and rocker bottom feet. Left lobe dominance of the liver and mislocation of the ileocecal junction and appendix were noted on internal examination. The brain was small (700 g) and poorly developed. Microscopically it showed an absence of neurons in the olivary and dentate nuclei, absence of Purkinje cells in the cerebellum, severe depletion of internal granular cells in the cerebellum, and cerebellar dysplasia. Fat infiltration was noted in an unusual distribution in several organs including a pattern in the heart consistent with arrythmogenic right ventricular dysplasia (ARVD). Findings of this mosaic chromosomal karyotype have not been previously described. This report will discuss this individuals physical findings and their relation to similar monochromosomal aberrations.

A reciprocal translocation 46,XY,t(8;9)(p11.2;q13) in a bladder exstrophy patient disrupts CNTNAP3 and presents evidence of a pericentromeric duplication on chromosome 9.

A patient with sporadic bladder exstrophy and de novo apparently balanced chromosomal translocation 46,XY,t(8;9)(p11.2;q13) was analyzed by fluorescence in situ hybridization (FISH) and molecular methods. We were able to map both translocation breakpoints to single genomic clones. The chromosome 8p11.2 breakpoint was mapped to BAC clone RP4-547J18, predicted to contain several hypothetical genes. Characterization of the chromosome 9q13 breakpoint indicated a disruption in the 5' region of CNTNAP3 within BAC RP11-292B8. This observation suggests possible involvement of CNTNAP3 in the etiology of bladder exstrophy. Additionally, FISH analysis identified several genomic copies of CNTNAP3 on both sides of the chromosome 9 centromere flanking the polymorphic heterochromatin. Northern blot analysis of lymphoblast and bladder RNA confirmed CNTNAP3 transcripts in these tissues and did not show abnormal CNTNAP3 expression in the proband and two unrelated patients with bladder exstrophy. The identification of multiple copies of three BAC clones in the proband, his parents, and unrelated controls suggests that duplications of CNTNAP3 and the surrounding genomic region have occurred as a result of repeated events of unequal crossing over and pericentric inversions during chromosome 9 evolution.

Prenatal detection of an interstitial deletion in 4p15 in a fetus with an increased nuchal skin fold measurement.

OBJECTIVES: The detection of an increased nuchal translucency (NT) or nuchal fold (NF) measurement is associated with an increased risk of common aneuploidies. Only rarely is it associated with other types of chromosome abnormalities. We report the prenatal finding of an increased NF in a fetus with an interstitial 4p deletion. METHODS: Standard karyotype analysis was followed by FISH with research generated BAC probes to precisely map the 4p deletion. RESULTS: The karyotype of the fetus was determined to be 46,XX,del(4)(p15.2p16.1) by G-banding analysis and was refined to 46,XX,del(4) (p15.1p15.32) after FISH analysis. The breakpoints were narrowed to 150 kb regions on each side. The deletion is approximately 14.5 Mb, containing approximately 47 genes. CONCLUSIONS: We report a case of an increased NF measurement associated with a 4p deletion. A literature review revealed a previous case of a 4p deletion in a fetus with an increased NT. Since chromosome deletions are rarely associated with an increased NT or NF, we believe it is significant that a 4p deletion has now been found in two unrelated cases. We mapped the deletion with BAC probes, generating a list of possible candidate genes involved in the pathogenesis of increased nuchal skin folds.

Reevaluating confined placental mosaicism.

Chromosomal mosaicism was found in 38 of 4,000 chorionic villus samples examined from 1998 to 2003. A small fraction of these (5/38) were confirmed as true mosaics by analysis of amniotic fluid. Twenty-nine cases that fit the definition of confined placental mosaicism were followed with clinical and cytogenetic analysis throughout the pregnancy, at birth and in a few cases into infancy. This was done to determine the prognostic interpretation of prenatal cytogenetic results from multiple specimens in a single pregnancy and thus allow for reevaluation of the genetic counseling. In 2 of these 29 cases, low-level mosaicism was found in the neonate, and in 1 of these the chromosome abnormality is probably the cause of the resulting minor phenotypic abnormalities. Families face unique difficulties when confined placental mosaicism is the prenatal diagnosis, and it is extremely important that the counseling they receive takes into consideration the unlikely possibility of the placental abnormality appearing in fetal tissues.

Transcript level alterations reflect gene dosage effects across multiple tissues in a mouse model of down syndrome.

Human trisomy 21, which results in Down syndrome (DS), is one of the most complicated congenital genetic anomalies compatible with life, yet little is known about the molecular basis of DS. It is generally accepted that chromosome 21 (Chr21) transcripts are overexpressed by about 50% in cells with an extra copy of this chromosome. However, this assumption is difficult to test in humans due to limited access to tissues, and direct support for this idea is available for only a few Chr21 genes or in a limited number of tissues. The Ts65Dn mouse is widely used as a model for studies of DS because it is at dosage imbalance for the orthologs of about half of the 284 Chr21 genes. Ts65Dn mice have several features that directly parallel developmental anomalies of DS. Here we compared the expression of 136 mouse orthologs of Chr21 genes in nine tissues of the trisomic and euploid mice. Nearly all of the 77 genes which are at dosage imbalance in Ts65Dn showed increased transcript levels in the tested tissues, providing direct support for a simple model of increased transcription proportional to the gene copy number. However, several genes escaped this rule, suggesting that they may be controlled by additional tissue-specific regulatory mechanisms revealed in the trisomic situation.

In utero hematopoietic stem cell transplantation with haploidentical donor adult bone marrow in a canine model.

OBJECTIVE: Chimerism can be achieved in a canine model of in utero bone marrow transplantation with > or =1 x 10(8) CD34(+) haploidentical donor cells per kilogram without graft-versus-host disease. STUDY DESIGN: In utero bone marrow transplantation was performed by ultrasound-guided intraperitoneal infusion in 30- to 41-day-old canines with CD34(+) selected cells from paternal bone marrow at doses of 1.3 x 10(8) to 2.5 x 10(10) CD34(+) cells/kg. A method for marking control littermates was developed with intraperitoneal ethiodol. Postnatal studies included histologic, fluorescent in situ hybridization canine Y probe, and polymerase chain reaction-based chimerism analyses. RESULTS: Term survival was 86% to 100% for transplantations > or =34 days versus 14% and 43% at 30 and 31 days. Microchimerism (<1%) was demonstrated in tissues from 4 informative litters that included thymus, liver, skin, spleen, and intestine. Neither gestational age nor donor CD34 cell dosage altered the level of engraftment in these experiments. There was no evidence of graft-versus-host disease. CONCLUSION: In utero bone marrow transplantation in a canine model achieves microchimerism with high CD34(+) cell doses.