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1.  46,XY disorder of sex development and developmental delay associated with a novel 9q33.3 microdeletion encompassing NR5A1 
European journal of medical genetics  2013;56(11):10.1016/j.ejmg.2013.09.006.
Steroidogenic factor 1 (SF1) is a nuclear receptor encoded by the NR5A1 gene. SF1 affects both sexual and adrenal development through the regulation of target gene expression. Genotypic male and female SF1 knockout mice have adrenal and gonadal agenesis with persistent Müllerian structures and early lethality. There have been several reports of NR5A1 mutations in individuals with 46,XY complete gonadal dysgenesis (CGD) or other disorders of sex development (DSD) with or without an adrenal phenotype. To date microdeletions involving NR5A1 have been reported in only two patients with DSDs. We report a novel microdeletion encompassing NR5A1 in a patient with 46,XY DSD and developmental delay. The phenotypically female patient initially presented with mild developmental delay and dysmorphisms. Chromosome analysis revealed a 46,XY karyotype. A 1.54 Mb microdeletion of chromosome 9q33.3 including NR5A1 was detected by array CGH and confirmed by FISH. Normal maternal FISH results indicated that this was most likely a de novo event. Since most NR5A1 mutations have been ascertained through gonadal or adrenal abnormalities, the additional findings of developmental delay and minor facial dysmorphisms are possibly related to haploinsufficiency of other genes within the 1.54 Mb deleted region. This report further confirms the role of NR5A1 deletions in 46,XY DSD and reinforces the utility of aCGH in the work up of DSDs of unclear etiology.
PMCID: PMC3880784  PMID: 24056159
NR5A1; SF1; 46,XY disorder of sex development; 46,XY DSD; 9q33 microdeletion
2.  Identification and Purification of Human Induced Pluripotent Stem Cell-Derived Atrial-Like Cardiomyocytes Based on Sarcolipin Expression 
PLoS ONE  2014;9(7):e101316.
The use of human stem cell-derived cardiomyocytes to study atrial biology and disease has been restricted by the lack of a reliable method for stem cell-derived atrial cell labeling and purification. The goal of this study was to generate an atrial-specific reporter construct to identify and purify human stem cell-derived atrial-like cardiomyocytes. We have created a bacterial artificial chromosome (BAC) reporter construct in which fluorescence is driven by expression of the atrial-specific gene sarcolipin (SLN). When purified using flow cytometry, cells with high fluorescence specifically express atrial genes and display functional calcium handling and electrophysiological properties consistent with atrial cardiomyocytes. Our data indicate that SLN can be used as a marker to successfully monitor and isolate hiPSC-derived atrial-like cardiomyocytes. These purified cells may find many applications, including in the study of atrial-specific pathologies and chamber-specific lineage development.
PMCID: PMC4092021  PMID: 25010565
3.  Large inverted repeats within Xp11.2 are present at the breakpoints of isodicentric X chromosomes in Turner syndrome 
Human Molecular Genetics  2010;19(17):3383-3393.
Turner syndrome (TS) results from whole or partial monosomy X and is mediated by haploinsufficiency of genes that normally escape X-inactivation. Although a 45,X karyotype is observed in half of all TS cases, the most frequent variant TS karyotype includes the isodicentric X chromosome alone [46,X,idic(X)(p11)] or as a mosaic [46,X,idic(X)(p11)/45,X]. Given the mechanism of idic(X)(p11) rearrangement is poorly understood and breakpoint sequence information is unknown, this study sought to investigate the molecular mechanism of idic(X)(p11) formation by determining their precise breakpoint intervals. Karyotype analysis and fluorescence in situ hybridization mapping of eight idic(X)(p11) cell lines and three unbalanced Xp11.2 translocation lines identified the majority of breakpoints within a 5 Mb region, from ∼53 to 58 Mb, in Xp11.1–p11.22, clustering into four regions. To further refine the breakpoints, a high-resolution oligonucleotide microarray (average of ∼350 bp) was designed and array-based comparative genomic hybridization (aCGH) was performed on all 11 idic(X)(p11) and Xp11.2 translocation lines. aCGH analyses identified all breakpoint regions, including an idic(X)(p11) line with two potential breakpoints, one breakpoint shared between two idic(X)(p11) lines and two Xp translocations that shared breakpoints with idic(X)(p11) lines. Four of the breakpoint regions included large inverted repeats composed of repetitive gene clusters and segmental duplications, which corresponded to regions of copy-number variation. These data indicate that the rearrangement sites on Xp11.2 that lead to isodicentric chromosome formation and translocations are probably not random and suggest that the complex repetitive architecture of this region predisposes it to rearrangements, some of which are recurrent.
PMCID: PMC2916707  PMID: 20570968
4.  Patient-specific induced pluripotent stem cell derived models of LEOPARD syndrome 
Nature  2010;465(7299):808-812.
Generation of reprogrammed induced pluripotent stem cells (iPSC) from patients with defined genetic disorders promises important avenues to understand the etiologies of complex diseases, and the development of novel therapeutic interventions. We have generated iPSC from patients with LEOPARD syndrome (LS; acronym of its main features: Lentigines, Electrocardiographic abnormalities, Ocular hypertelorism, Pulmonary valve stenosis, Abnormal genitalia, Retardation of growth and Deafness), an autosomal dominant developmental disorder belonging to a relatively prevalent class of inherited RAS-MAPK signaling diseases, which also includes Noonan syndrome (NS), with pleiomorphic effects on several tissues and organ systems1,2. The patient-derived cells have a mutation in the PTPN11 gene, which encodes the SHP2 phosphatase. The iPSC have been extensively characterized and produce multiple differentiated cell lineages. A major disease phenotype in patients with LEOPARD syndrome is hypertrophic cardiomyopathy. We show that in vitro-derived cardiomyocytes from LS-iPSC are larger, have a higher degree of sarcomeric organization and preferential localization of NFATc4 in the nucleus when compared to cardiomyocytes derived from human embryonic stem cells (HESC) or wild type (wt) iPSC derived from a healthy brother of one of the LS patients. These features correlate with a potential hypertrophic state. We also provide molecular insights into signaling pathways that may promote the disease phenotype.
PMCID: PMC2885001  PMID: 20535210
5.  An atypical deletion of the Williams–Beuren syndrome interval implicates genes associated with defective visuospatial processing and autism 
Journal of Medical Genetics  2006;44(2):136-143.
During a genetic study of autism, a female child who met diagnostic criteria for autism spectrum disorder, but also exhibited the cognitive–behavioural profile (CBP) associated with Williams–Beuren syndrome (WBS) was examined. The WBS CBP includes impaired visuospatial ability, an overly friendly personality, excessive non‐social anxiety and language delay.
Using array‐based comparative genomic hybridisation (aCGH), a deletion corresponding to BAC RP11‐89A20 in the distal end of the WBS deletion interval was detected. Hemizygosity was confirmed using fluorescence in situ hybridisation and fine mapping was performed by measuring the copy number of genomic DNA using quantitative polymerase chain reaction.
The proximal breakpoint was mapped to intron 1 of GTF2IRD1 and the distal breakpoint lies 2.4–3.1 Mb towards the telomere. The subject was completely hemizygous for GTF2I, commonly deleted in carriers of the classic ∼1.5 Mb WBS deletion, and GTF2IRD2, deleted in carriers of the rare ∼1.84 Mb WBS deletion.
Hemizygosity of the GTF2 family of transcription factors is sufficient to produce many aspects of the WBS CBP, and particularly implicate the GTF2 transcription factors in the visuospatial construction deficit. Symptoms of autism in this case may be due to deletion of additional genes outside the typical WBS interval or remote effects on gene expression at other loci.
PMCID: PMC2598069  PMID: 16971481
6.  Multiplex ligation-dependent probe amplification for genetic screening in autism spectrum disorders: Efficient identification of known microduplications and identification of a novel microduplication in ASMT 
BMC Medical Genomics  2008;1:50.
It has previously been shown that specific microdeletions and microduplications, many of which also associated with cognitive impairment (CI), can present with autism spectrum disorders (ASDs). Multiplex ligation-dependent probe amplification (MLPA) represents an efficient method to screen for such recurrent microdeletions and microduplications.
In the current study, a total of 279 unrelated subjects ascertained for ASDs were screened for genomic disorders associated with CI using MLPA. Fluorescence in situ hybridization (FISH), quantitative polymerase chain reaction (Q-PCR) and/or direct DNA sequencing were used to validate potential microdeletions and microduplications. Methylation-sensitive MLPA was used to characterize individuals with duplications in the Prader-Willi/Angelman (PWA) region.
MLPA showed two subjects with typical ASD-associated interstitial duplications of the 15q11-q13 PWA region of maternal origin. Two additional subjects showed smaller, de novo duplications of the PWA region that had not been previously characterized. Genes in these two novel duplications include GABRB3 and ATP10A in one case, and MKRN3, MAGEL2 and NDN in the other. In addition, two subjects showed duplications of the 22q11/DiGeorge syndrome region. One individual was found to carry a 12 kb deletion in one copy of the ASPA gene on 17p13, which when mutated in both alleles leads to Canavan disease. Two subjects showed partial duplication of the TM4SF2 gene on Xp11.4, previously implicated in X-linked non-specific mental retardation, but in our subsequent analyses such variants were also found in controls. A partial duplication in the ASMT gene, located in the pseudoautosomal region 1 (PAR1) of the sex chromosomes and previously suggested to be involved in ASD susceptibility, was observed in 6–7% of the cases but in only 2% of controls (P = 0.003).
MLPA proves to be an efficient method to screen for chromosomal abnormalities. We identified duplications in 15q11-q13 and in 22q11, including new de novo small duplications, as likely contributing to ASD in the current sample by increasing liability and/or exacerbating symptoms. Our data indicate that duplications in TM4SF2 are not associated with the phenotype given their presence in controls. The results in PAR1/PAR2 are the first large-scale studies of gene dosage in these regions, and the findings at the ASMT locus indicate that further studies of the duplication of the ASMT gene are needed in order to gain insight into its potential involvement in ASD. Our studies also identify some limitations of MLPA, where single base changes in probe binding sequences alter results. In summary, our studies indicate that MLPA, with a focus on accepted medical genetic conditions, may be an inexpensive method for detection of microdeletions and microduplications in ASD patients for purposes of genetic counselling if MLPA-identified deletions are validated by additional methods.
PMCID: PMC2588447  PMID: 18925931

Results 1-6 (6)