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Philippos C Patsalis

Publications and source records attributed to Philippos C Patsalis.

12 recordsLinked to original sources
PubMed2006

Detection of small genomic imbalances using microarray-based multiplex amplifiable probe hybridization.

Array-based genome-wide screening methods were recently introduced to clinical practice in order to detect small genomic imbalances that may cause severe genetic disorders. The continuous advancement of such methods plays an extremely important role in diagnostic genetics and medical genomics. We have modified and adapted the original multiplex amplifiable probe hybridization (MAPH) to a novel microarray format providing an important new diagnostic tool for detection of small size copy-number changes in any locus of human genome. Here, we describe the new array-MAPH diagnostic method and show proof of concept through fabrication, interrogation and validation of a human chromosome X-specific array. We have developed new bioinformatic tools and methodology for designing and producing amplifiable hybridization probes (200-600 bp) for array-MAPH. We designed 558 chromosome X-specific probes with median spacing 238 kb and 107 autosomal probes, which were spotted onto microarrays. DNA samples from normal individuals and patients with known and unknown chromosome X aberrations were analyzed for validation. Array-MAPH detected exactly the same deletions and duplications in blind studies, as well as other unknown small size deletions showing its accuracy and sensitivity. All results were confirmed by fluorescence in situ hybridization and probe-specific PCR. Array-MAPH is a new microarray-based diagnostic tool for the detection of small-scale copy-number changes in complex genomes, which may be useful for genotype-phenotype correlations, identification of new genes, studying genetic variation and provision of genetic services.

Chromosome Aberrations↗
PubMed2006

Array-CGH analysis and clinical description of 2q37.3 de novo subtelomeric deletion.

We report on a 13-year-old girl with normal karyotype and a de novo cryptic terminal deletion of chromosome 2q, detected by subtelomeric FISH analysis. Further investigation with array-CGH analysis using the 1Mb resolution Spectral Chip 2600 (Spectral Genomics) confirmed the deletion and also showed a deletion of four additional clones. No other abnormalities were detected by array-CGH. FISH studies using 8 BAC-probes were performed for fine mapping of the deletion and confirmed the array results. FISH analysis showed that the deletion breakpoint lies between clones RP11-84G18 and RP11-83N2 (physical distance between clones 0.36Mb) and extends to the telomere. The size of the deletion was estimated to be about 6.4-6.7Mb. Clinical findings include: developmental delay, severe behavioural disturbances, growth-pubertal retardation, congenital conductive mild hearing loss, growth hormone deficiency, compensate hypothyroidism, dysmorphic facial features, excessive joint hypermobility, brachymetaphalangy, abnormal dermatoglyphics and a history of neonatal laryngomalacia, hypotonia and umbilical hernia. The phenotype of our patient is in keeping with those of the literature, with the exception of cardiovascular, urogenital, neurological anomalies and eczema, which were not observed. The report of the clinical and molecular presentation of similar cases will allow accurate phenotype-genotype correlation and proper genetic counseling of the family.

Abnormalities, Multiple↗
PubMed2006

The cypriot and Iranian National Mutation Frequency Databases.

The National Mutation Frequency Databases are continuously updated mutation depositories, which contain extensive information over the described genetic heterogeneity of an ethnic group or population. Here, we report the construction of the Cypriot (http://www.goldenhelix.org/cypriot) and Iranian National Mutation Frequency Databases (http://www.goldenhelix.org/iranian), both derived from an academic effort to provide high quality and up-to-date information on the underlying genetic heterogeneity of inherited disorders in the Cypriot and Iranian populations, respectively. Both databases have been built and maintained online using ETHNOS platform, a specialized software, which provides the means for national mutation database construction and curation. Each database contains brief summaries of the various genetic disorders studied for each population, and an easy-to-use query interface provides, both to specialist as well as to non-specialist users (i.e. patients and their families), instant access to the list and frequencies of the different mutations responsible for the inherited disorders in these populations. Furthermore, numerous links to the respective Online Mendelian Inheritance in Man (OMIM) entries and, when available, to the locus-specific databases fruitfully integrate the databases content into a single Web site. Both databases can serve as valuable online tools for molecular genetic testing of inherited disorders in these populations and could potentially motivate further investigations of yet unknown genetic diseases in the Cypriot and Iranian populations.

Cyprus↗
PubMed2005

Identification of high frequency of Y chromosome deletions in patients with sex chromosome mosaicism and correlation with the clinical phenotype and Y-chromosome instability.

A mosaic karyotype consisting of a 45,X cell line and a second cell line containing a normal or an abnormal Y chromosome is relatively common and is associated with a wide spectrum of clinical phenotypes. The aim of this study was to investigate patients with such a mosaic karyotype for Y chromosome material loss and then study the possible association of the absence of these regions with the phenotype, diagnosis, and Y-chromosome instability. We studied 17 clinically well-characterized mosaic patients whose karyotype consisted of a 45,X cell line and a second cell line containing a normal or an abnormal Y chromosome. The presence of the Y chromosome centromere was verified by fluorescence in situ hybridization (FISH) and was then characterized by 44 Y-chromosome specific-sequence tagged site (STS) markers. This study identifies a high frequency of Yq chromosome deletions (47%). The deletions extend from interval 5 to 7 sharing a common deleted interval (6F), which overlaps with the azoospermia factor region (AZF) region. This study finds no association between Y-chromosome loci hosting genes other than SRY, and the phenotypic sex, the diagnosis, and the phenotype of the patients. Furthermore, this study shows a possible association of these deletions with Y-chromosome instability.

Cell Line↗
PubMed2005

5alpha-reductase 2 gene mutations in three unrelated patients of Greek Cypriot origin: identification of an ancestral founder effect.

INTRODUCTION: 5alpha-Steroid reductase deficiency (5alphaSRD) is an autosomal recessive enzymatic deficiency. Mutations in the 5alpha-steroid reductase type 2 gene (SRD5A2) result in male pseudohermaphroditism caused by decreased dihydrotestosterone (DHT) synthesis--a key hormone of virilization of male external genitalia. AIM: To study for the first time patients from the Greek Cypriot population, describe their clinical characteristics, and identify the genetic mutations of the SRD5A2 gene. PATIENTS AND METHODS: Three unrelated patients with 46,XY karyotype born with ambiguous genitalia were examined. Patient 1 was raised as a girl and was diagnosed with partial androgen insensitivity syndrome, based on the clinical picture and incomplete laboratory investigation at the age of 4 years, and underwent gonadectomy. For this patient sequencing analysis of all five exons of the SRD5A2 gene and exons 2 to 8 of the androgen receptor (AR) gene was performed. Patients 2 and 3 were also born with ambiguous genitalia. The hCG test for these two patients was informative of 5alphaSRD, as it showed elevated T/DHT ratio after stimulation. Despite genetic counseling, both families decided to raise their infants as females because of severe under-virilization. Sequencing of the SRD5A2 gene was also completed for both patients. RESULTS: No mutations were found in the AR sequence for patient 1. Patients 1 and 3 were found homozygous for the mutation A/G at splice junction intron 1/exon 2 and patient 2 was found heterozygous for the same A/G substitution and also heterozygous for an additional mutation, Pro181Leu, in exon 3. CONCLUSIONS: The same mutation in the SRD5A2 gene was identified in three unrelated patients, in both homozygous and heterozygous form. This splice mutation was previously reported in Turkish patients. This underlying genetic abnormality may be characteristic for the Eastern Mediterranean region and is likely due to an ancestor effect.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2005

Complete androgen insensitivity syndrome caused by the R855H mutation in the androgen receptor gene.

Complete androgen insensitivity syndrome (CAIS) is characterized by a completely female phenotype in a 46,XY individual and is caused by mutations in the androgen receptor (AR) gene. A 5 year-old girl presented with bilateral hernia and was noted to have bilateral testes. She had a 46,XY karyotype and was diagnosed with CAIS. To identify the underlying mutation, the exons 2 to 8 of the AR gene were amplified by PCR using sets of known primers and reaction conditions. The results of the mutational analysis for the AR showed the presence of the R855H mutation; her mother was found to be heterozygous and both her 46,XX sister and her aunt had a normal AR gene. This mutation, is the result of a guanine to adenine transition in codon 855 at position 2926 in exon 7 of the AR gene, which causes an alteration of the coding nucleotide triad from CGC to CAC, which subsequently causes the substitution from arginine to histidine in the amino acid sequence of the receptor protein molecule. The same mutation has been reported to cause variable phenotypic expression, which could be explained by the presence of additional co-activating factors modifying the biological activity of the AR. The identification of an AR mutation in a girl with CAIS provides important information, because of the syndrome's genetic heterogeneity. This report emphasizes the fact that genetic determinants outside the coding sequence of the AR can influence the function of the AR protein molecule. Phenotypic expression of the mutation may be used for the construction of maps of functional domains of the AR.

Androgen-Insensitivity Syndrome↗
PubMed2004

Fluorescence in situ hybridization characterization of apparently balanced translocation reveals cryptic complex chromosomal rearrangements with unexpected level of complexity.

The great majority of apparently balanced translocations are associated with multiple miscarriages and normal phenotype. Several mechanisms have been proposed to explain how a small percentage of apparently balanced translocations are associated with abnormal phenotypes. One of the proposed mechanisms that have not been well investigated is that apparently balanced translocations may host 'cryptic' complex chromosomal rearrangements (CCRs). To test this hypothesis, this study investigated 20 non-preselected cases with apparently balanced translocations in order to determine the presence of cryptic CCRs. Multiprobe subtelomeric and whole chromosome paint FISH analyses revealed and further characterized three cryptic CCRs. Two out of three CCRs showed an unexpected level of complexity. The results of this study provided evidence that the link between an apparently balanced rearrangement and the appearance of abnormal phenotype may be partly explained by the presence of cryptic CCRs. The results also suggested that what is reported as apparently balanced translocation by classical cytogenetics may host cryptic CCRs, which could be more common than initially thought. Furthermore, the use of both of the above-mentioned FISH methodologies was absolutely necessary to detect the CCRs.

Gene Rearrangement↗
PubMed2003

A gene for nonsyndromic X-linked mental retardation (MRX77) maps to Xq12-Xq21.33.

Nonsyndromic X-linked mental retardation (MRX) is a highly heterogeneous condition in which mental retardation appears to be the only consistent manifestation. According to the most recent data, 77 MRX families with a lod score of >2 have been mapped and eight genes have been cloned. We hereby report on a linkage analysis performed on a Greek family with apparently nonsyndromic MRX. The affected males have moderate to severe mental retardation, severe speech problems, and aggressive behavior. Two-point linkage analysis with 26 polymorphic markers spanning the entire X chromosome was carried out. We could assign the causative gene to a 27 Mb interval in Xq12-Xq21.33. The maximum LOD score was found for markers DXS1225, DXS8114, and DXS990 at 2.36, 2.06, 2.06, respectively at theta = 0.00. Recombination was observed for DXS983 at the proximal side and DXS6799 at the distal side. Nineteen other MRX families have been described with a partial overlapping disease gene interval in proximal Xq. No mutations were found in the MRX77 family for three known or candidate MRX genes, from this region OPHN1, RSK4, and ATR-X. These data indicate that the Xq12-Xq21.33 interval contains at least one additional MRX gene.

Chromosome Mapping↗
PubMed2002

Effects of transmission of Y chromosome AZFc deletions.

Deletions of specific regions on the Y chromosome cause male infertility. Recent advances in infertility treatment allow Y chromosome deletions to be transmitted to male offspring with the assumption that there will be no clinical consequences other than infertility in adult life. We screened 12 patients, who had a 45X/46XY karyotype and presented with Turner stigmata or sexual ambiguities, or both, for Y chromosome microdeletions with PCR. A third of these patients had Y chromosome microdeletions of distal Yq, the most common microdeletion seen in infertile men with azoospermia or severe oligozoospermia. Transmission of Y chromosome microdeletions could potentially have severe clinical consequences other than male infertility, such as the development of sexual ambiguities and Turner stigmata.

Adult↗
PubMedDate not supplied

MAPH: from gels to microarrays.

The development of accurate and sensitive methodologies to detect small chromosomal imbalances (<3 Mb) is extremely important in clinical diagnostics and research in human genetics. The technique of array-comparative genomic hybridization (CGH) using BAC and PAC clones is very sensitive methodology and is rapidly becoming the method of choice for high-resolution screening of genomic copy-number changes. An alternative methodology to CGH is the multiplex amplifiable probe hybridization (MAPH) methodology, a DNA based method that allows the accurate and reliable determination of changes in copy number in "known" or "unknown locations" in the human genome. MAPH uses probes of 100-500 bp in size, that can be specifically designed for any gene or locus in the genome and cover any gene exons, the subtelomeric or subcentromeric regions, any chromosomal segment, a whole chromosome or the total human genome. MAPH can provide extremely high resolution and enable the sensitive detection of loss or gain of genomic DNA sequences as small as 150 bp. Very recently we succeeded in the advancement of MAPH from gel and capillary analyses to microarrays. The array-MAPH methodology offers an alternative methodology to array-CGH and provides a new sensitive microarray-based method including several advantages for the detection of copy number changes in the human genome.

DNA↗