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PubMed2006

A gender-moderated effect of a functional COMT polymorphism on prefrontal brain morphology and function in velo-cardio-facial syndrome (22q11.2 deletion syndrome).

Caused by a microdeletion at the q11.2 locus of chromosome 22, velo-cardio-facial syndrome (also known as VCFS, 22q11 deletion syndrome, DiGeorge sequence, and conotruncal anomalies face syndrome) is associated with a distinctive physical, neurocognitive, and psychiatric phenotype. Increasing interest has centered on identifying the candidate genes within the deleted region that may contribute to this phenotype. One attractive candidate gene is catechol-O-methyltransferase (COMT) because it encodes for a protein that degrades dopamine. Variability in COMT activity is related to a Val158Met polymorphism that has been implicated in prefrontal lobe cognitive and neuropsychiatric function. We examined the effect of this polymorphism on prefrontal anatomy and frontally-mediated neuropsychological function in 58 children with VCFS, 26 who were hemizygous for the Met allele and 32 for the Val allele. We found an allele by gender interaction effect on the volumes of the dorsal prefrontal and orbital prefrontal cortices. We did not find significant allele or gender by allele effects on neuropsychological tasks, although girls with the Met allele tended to perform better on the Wisconsin card sorting task. These data suggest that this functional COMT polymorphism may play a gender-moderated role in determining the neuroanatomic phenotype of individuals with VCFS. Longitudinal evaluation of these children is essential in order to identify potential clinical implications of this allele by gender interaction.

Abnormalities, Multiple↗
PubMed2007

Schizophrenic-like neurocognitive deficits in children and adolescents with 22q11 deletion syndrome.

22q11.2 Deletion Syndrome (22q11DS) is the most common genetic microdeletion syndrome affecting humans. The syndrome is associated with general cognitive impairments and specific deficits in visual-spatial ability, non-verbal reasoning, and planning skills. 22q11DS is also associated with behavioral and psychiatric abnormalities, including a markedly elevated risk for schizophrenia. Research findings indicate that people with schizophrenia, as well as those identified as schizoptypic, show specific cognitive deficits in the areas of sustained attention, executive functioning, and verbal working memory. The present study examined such schizophrenic-like cognitive deficits in children and adolescents with 22q11DS (n = 26) and controls (n = 25) using a cross-sectional design. As hypothesized, 22q11DS participants exhibited deficits in intelligence, achievement, sustained attention, executive functioning, and verbal working memory compared to controls. Furthermore, deficits in attention and executive functioning were more pronounced in the 22q11DS sample relative to general cognitive impairment. These findings suggest that the same pattern of neuropsychological impairment seen in patients with schizophrenia is present in non-psychotic children identified as at-risk for the development of schizophrenia based on a known genetic risk marker.

Adolescent↗
PubMed2005

NSD1 mutations in Sotos syndrome.

Sotos syndrome is a genetic disorder characterized by a typical facial appearance, macrocephaly, accelerated growth, developmental delay, and a variable range of associated abnormalities. The NSD1 gene was recently found to be responsible for Sotos syndrome, and more than 150 patients with NSD1 alterations have been identified. A significant ethnic difference is found in the prevalence of different types of mutation, with a high percentage of microdeletions identified in Japanese Sotos syndrome patients and with intragenic mutations in most non-Japanese patients. NSD1 aberrations are rather specific for Sotos syndrome, but have also been detected in patients lacking one or more major criteria of the disorder, namely overgrowth, macrocephaly, and advanced bone age. Thus, new diagnostic criteria should be considered. Studies have reported different frequencies of mutations versus non-mutations in Sotos syndrome, thus indicating allelic or locus hetereogeneity. Although some authors have suggested genotype/phenotype correlations, further studies are needed.

Abnormalities, Multiple↗
PubMed1996

Cortical myoclonus in Angelman syndrome.

Angelman syndrome (AS) results from lack of genetic contribution from maternal chromosome 15q11-13. This region encompasses three GABAA receptor subunit genes (beta3, alpha5, and gamma3). The characteristic phenotype of AS is severe mental retardation, ataxic gait, tremulousness, and jerky movements. We studied the movement disorder in 11 AS patients, aged 3 to 28 years. Two patients had paternal uniparental disomy for chromosome 15, 8 had a >3 Mb deletion, and 1 had a microdeletion involving loci D15S10, D15S113, and GABRB3. All patients exhibited quasicontinuous rhythmic myoclonus mainly involving hands and face, accompanied by rhythmic 5- to 10-Hz electroencephalographic (EEG) activity. Electromyographic bursts lasted 35 +/- 13 msec and had a frequency of 11 +/- 2.4 Hz. Burst-locked EEG averaging in 5 patients, generated a premyoclonus transient preceding the burst by 19 +/- 5 msec. A cortical spread pattern of myoclonic cortical activity was observed. Seven patients also demonstrated myoclonic seizures. No giant somatosensory evoked potentials or C-reflex were observed. The silent period following motor evoked potentials was shortened by 70%, indicating motor cortex hyperexcitability. Treatment with piracetam in 5 patients significantly improved myoclonus. We conclude that spontaneous, rhythmic, fast-bursting cortical myoclonus is a prominent feature of AS.

Adolescent↗
PubMed2006

High-density single nucleotide polymorphism screen in a large multiplex neural tube defect family refines linkage to loci at 7p21.1-pter and 2q33.1-q35.

BACKGROUND: Neural tube defects (NTDs) are considered complex, with both genetic and environmental factors implicated. To date, no major causative genes have been identified in humans despite several investigations. The first genomewide screen in NTDs demonstrated evidence of linkage to chromosomes 7 and 10. This screen included 44 multiplex families and consisted of 402 microsatellite markers spaced approximately 10 cM apart. Further investigation of the genomic screen data identified a single large multiplex family, pedigree 8776, as primarily driving the linkage results on chromosome 7. METHODS: To investigate this family more thoroughly, a high-density single nucleotide polymorphism (SNP) screen was performed. Two-point and multipoint linkage analyses were performed using both parametric and nonparametric methods. RESULTS: For both the microsatellite and SNP markers, linkage analysis suggested the involvement of a locus or loci proximal to the telomeric regions of chromosomes 2q and 7p, with both regions generating a LOD* score of 3.0 using a nonparametric identity by descent relative sharing method. CONCLUSIONS: The regions with the strongest evidence for linkage map proximal to the telomeres on these two chromosomes. In addition to mutations and/or variants in a major gene, these loci may harbor a microdeletion and/or translocation; potentially, polygenic factors may also be involved. This single family may be promising for narrowing the search for NTD susceptibility genes.

Chromosomes, Human, Pair 2↗
PubMed2006

DiGeorge syndrome and pharyngeal apparatus development.

DiGeorge syndrome is the most frequent microdeletion syndrome in humans, and is characterized by cardiovascular, thymic and parathyroid, and craniofacial anomalies. The underlying cause is disturbed formation of the pharyngeal apparatus, a transient structure present during vertebrate development that gives rise to endocrine glands, craniofacial tissue, and the cardiac outflow tract. The pharyngeal apparatus is composed of derivatives of ectoderm, endoderm, mesoderm and the neural crest. Thus, complex interactions between cell types from different origins have to be orchestrated in the correct spatiotemporal manner to establish proper formation of the pharyngeal system. The analysis of engineered mouse mutants developing a phenotype resembling DiGeorge syndrome has revealed genes and signalling pathways crucial for this process. Intriguingly, these mouse models reveal that interference with either of two distinct phases of pharyngeal apparatus development can contribute to the aetiology of DiGeorge syndrome.

Animals↗
PubMed2007

The folate metabolic enzyme ALDH1L1 is restricted to the midline of the early CNS, suggesting a role in human neural tube defects.

Folate supplementation prevents up to 70% of human neural tube defects (NTDs), although the precise cellular and metabolic sites of action remain undefined. One possibility is that folate modulates the function of metabolic enzymes expressed in cellular populations involved in neural tube closure. Here we show that the folate metabolic enzyme ALDH1L1 is cell-specifically expressed in PAX3-negative radial glia at the midline of the neural tube during early murine embryogenesis. Midline restriction is not a general property of this branch of folate metabolism, as MTHFD1 displays broad and apparently ubiquitous expression throughout the neural tube. Consistent with previous work showing antiproliferative effects in vitro, ALDH1L1 upregulation during central nervous system (CNS) development correlates with reduced proliferation and most midline ALDH1L1(+) cells are quiescent. These data provide the first evidence for localized differences in folate metabolism within the early neural tube and suggest that folate might modulate proliferation via effects on midline Aldh1l1(+) cells. To begin addressing its role in neurulation, we analyzed a microdeletion mouse strain lacking Aldh1l1 and observed neither increased failure of neural tube closure nor detectable proliferation defects. Although these results indicate that loss-of-function Aldh1l1 mutations do not impair these processes in mice, the specific midline expression of ALDH1L1 and its ability to dominantly suppress proliferation in a folate responsive manner may suggest that mutations contributing to disease are gain-of-function, rather than loss-of-function. Moreover, a role for loss-of-function mutations in human NTDs remains possible, as Mthfr null mice do not develop NTDs even though MTHFR mutations increase human NTD risk.

Aldehyde Dehydrogenase↗
PubMed2002

Aberrations of the hSNF5/INI1 gene are restricted to malignant rhabdoid tumors or atypical teratoid/rhabdoid tumors in pediatric solid tumors.

The hSNF5/INI1 gene, which encodes a subunit of the SWI/SNF family of chromatin-remodeling complexes and is located at 22q11.2, has been reported as a tumor suppressor gene inactivated in malignant rhabdoid tumors (MRTs). We analyzed this gene in varieties of pediatric solid tumors including MRTs, using the reverse transcription-polymerase chain reaction (PCR) and PCR-single strand conformation polymorphism method. We found 5 homozygous deletions, 2 truncated mutations, one missense mutation, and one silent mutation of the hSNF5/INI1 gene in 7 MRT cell lines, and one homozygous deletion, one microdeletion, one splicing acceptor site mutation, and one absence of expression in 7 fresh tumor tissues of MRT and atypical teratoid (AT)/rhabdoid tumors (RTs). Homozygous deletions were also found in one (KYM-1) of 8 rhabdomyosarcoma (RMS) cell lines. To investigate characteristics of the KYM-1 cell line, we have established KYM-1 tumors in nude mice into which KYM-1 cells were transplanted. Notably, we found that MyoD1, known as a marker for RMS, was not expressed in the KYM-1 cell line as well as MRT cell lines and fresh tumors. Histopathologic, cytogenetic, and molecular studies of the KYM-1 cell line and KYM-1 tumors in nude mice have revealed that this RMS cell line should be MRT rather than RMS. RMS-carrying aberrations of the hSNF5/INI1 gene should be reevaluated. No aberrations of this gene were found in the other 34 cell lines or 80 fresh tumor specimens except the single nucleotide polymorphisms in the 3' noncoding region. These results suggest that alterations of the hSNF5/INI1 gene were restricted to MRTs or AT/RTs in pediatric solid tumors.

Adult↗
PubMed2005

High-resolution chromosome arm 5p array CGH analysis of small cell lung carcinoma cell lines.

Genomic amplification of regions on chromosome arm 5p has been observed frequently in small cell lung cancer (SCLC), implying the presence of multiple oncogenes on this arm. Although conventional comparative genomic hybridization (CGH) detects gross chromosomal copy number changes, gene discovery requires a higher-resolution approach in order to identify regions of alteration precisely. To identify candidate genes on this chromosome arm, we developed a high-resolution, 10-clone-per-megabase bacterial artificial chromosome CGH array for 5p and examined a panel of 15 SCLC cell lines. Utilization of this CGH array has allowed the fine-mapping of breakpoints to regions as small as 200 kb in a single experiment. In addition to reporting our observations of aberrations at the well-characterized SKP2 and TERT loci, we describe the identification of microdeletions that have escaped detection by conventional screens and the identification TRIO and ANKH as novel putative oncogenes.

Biomarkers, Tumor↗
PubMed1993

PRAD1/cyclin D1 proto-oncogene: genomic organization, 5' DNA sequence, and sequence of a tumor-specific rearrangement breakpoint.

PRAD1 (previously D11S287) is a putative proto-oncogene at 11q13, activated by overexpression through gene rearrangement or gene amplification in several types of human tumors including parathyroid adenomas, centrocytic lymphomas and other B-cell tumors with t(11;14), and breast cancers. PRAD1 (also CCND1) encodes cyclin D1, which may regulate the G1-S phase transition in the cell cycle. Here, we report the cloning and characterization of the chromosomal PRAD1/cyclin D1 gene and the sequence of its promoter region. The gene spans about 15 kb and has 5 exons; its promoter region has Sp1 binding sites and no obvious TATA box, characteristics of housekeeping genes and growth-regulating genes. Furthermore, an E2F binding motif present close to the major transcription start site may be involved in cell cycle-dependent expression of this gene. We also report the sequence of DNAs spanning joining regions of a reciprocal parathyroid hormone/PRAD1 gene rearrangement in a parathyroid adenoma. Comparison with normal sequences suggests that the rearrangement was not a simple break-and-ligate event, but rather involved multiple steps, including two microdeletions and a microinversion. Very short sequences conserved near the breakpoints and symmetrical elements in the eventually inverted DNA segment might have played a role in this illegitimate complex recombination, which may have similarities with a constitutional translocation in Duchenne muscular dystrophy.

Adenoma↗
PubMed2001

Eight novel ABCD1 gene mutations and three polymorphisms in patients with X-linked adrenoleukodystrophy: The first polymorphism causing an amino acid exchange.

X-ALD is a neurological disorder associated with inherited defects in the ABCD1 (ALD) gene located on Xq28 and with impaired peroxisomal very long-chain fatty acid beta-oxidation. We examined the ABCD1 gene in probands from 11 unrelated X-ALD Czech and Slovak families by the direct sequencing of cDNA or genomic PCR products. In 10 families there were 10 different mutations, eight of which were novel. The spectrum of mutations consists of six point mutations, three microdeletions (1bp, 2bp, 4 bp), and one large deletion (229bp). In the 11th family we detected two novel single-base pair substitutions in exon 1 (c.38 A>C and c.649 A>G), both causing amino acid exchanges (N13T and K217E). Expression studies revealed that only K217E is a deleterious mutation, because a plasmid encoding ALDP with K217E was ineffective in the restoration of defective beta-oxidation in X-ALD fibroblasts. The N13T amino acid exchange, on the other hand, did not affect ALDP function. Thus, N13T represents the first polymorphism causing an amino acid exchange in the ABCD1 gene. As this polymorphism was observed neither in 100 control alleles nor in 300 X-ALD patients who have been sequenced so far world-wide, it seems to be very rare or unique. Two additional novel polymorphisms were found by the sequencing of the ABCD1 gene from our patients: c.-59 C/T in the 5'untranslated region and c.2019 C/T (F673F) in exon 10. The frequencies of these two polymorphisms, were 11/150 and 2/150 control alleles, respectively.

5' Untranslated Regions↗
PubMed2004

Analysis of CBP (CREBBP) gene deletions in Rubinstein-Taybi syndrome patients using real-time quantitative PCR.

Rubinstein-Taybi syndrome (RTS) is a well-defined syndrome characterized by facial abnormalities, broad thumbs, broad big toes, and growth and mental retardation as the main clinical features. RTS was shown to be associated with disruption of the CREB-binding protein gene CBP (CREBBP), either by gross chromosomal rearrangements or by point mutations. Translocations and inversions involving chromosome band 16p13.3 form the minority of CBP mutations, whereas microdeletions occur more frequently (about 10%). Most deletion studies in RTS are performed by FISH analysis, and five cosmids must be used to cover the whole of the CBP gene, which spreads over 150 kb. Here we report the design of gene dosage assays by real-time quantitative PCR that are targeted on three exons located respectively at the 5' end (exon 2), in the middle (exon 12), and at the 3' end (exon 30) of the CBP gene. This technique proved to be efficient and powerful in finding deletions and complementary to the other available techniques, since it allowed us to identify deletions at the 3' end of the gene that had been missed by FISH analysis, and to refine some deletion breakpoints. Our results therefore suggest that real-time quantitative PCR is a useful technique to be included in the deletion search in RTS patients.

CREB-Binding Protein↗
PubMed2004

Molecular and functional analysis of SUMF1 mutations in multiple sulfatase deficiency.

Multiple sulfatase deficiency (MSD) is a rare disorder characterized by impaired activity of all known sulfatases. The gene mutated in this disease is SUMF1, which encodes a protein involved in a post-translational modification at the catalytic site of all sulfatases that is necessary for their function. SUMF1 strongly enhances the activity of sulfatases when coexpressed with sulfatase in Cos-7 cells. We performed a mutational analysis of SUMF1 in 20 MSD patients of different ethnic origin. The clinical presentation of these patients was variable, ranging from severe neonatal forms to mild phenotypes showing mild neurological involvement. A total of 22 SUMF1 mutations were identified, including missense, nonsense, microdeletion, and splicing mutations. We expressed all missense mutations in culture to study their ability to enhance the activity of sulfatases. Of the predicted amino acid changes, 11 (p.R349W, p.R224W, p.L20F, p.A348P, p.S155P, p.C218Y, p.N259I, p.A279V, p.R349Q, p.C336R, p.A177P) resulted in severely impaired sulfatase-enhancing activity. Two (p.R345C and p.P266L) showed a high residual activity on some, but not all, of the nine sulfatases tested, suggesting that some SUMF1 mutations may have variable effects on the activity of each sulfatase. This study compares, for the first time, clinical, biochemical, and molecular data in MSD patients. Our results show lack of a direct correlation between the type of molecular defect and the severity of phenotype.

Animals↗
PubMed2006

Rapid detection of submicroscopic chromosomal rearrangements in children with multiple congenital anomalies using high density oligonucleotide arrays.

Chromosomal rearrangements such as microdeletions and interstitial duplications are the underlying cause of many human genetic disorders. These disorders can manifest in the form of multiple congenital anomalies (MCA), which are a significant cause of morbidity and mortality in children. The major limitations of cytogenetic tests currently used for the detection of such chromosomal rearrangements are low resolution and limited coverage of the genome. Thus, it is likely that children with MCA may have submicroscopic chromosomal rearrangements that are not detectable by current techniques. We report the use of a commercially available, oligonucleotide-based microarray for genome-wide analysis of copy number alterations. First, we validated the microarray in patients with known chromosomal rearrangements. Next, we identified previously undetected, de novo chromosomal deletions in patients with MCA who have had a normal high-resolution karyotype and subtelomeric fluorescence in situ hybridization (FISH) analysis. These findings indicate that high-density, oligonucleotide-based microarrays can be successfully used as tools for the detection of chromosomal rearrangement in clinical samples. Their higher resolution and commercial availability make this type of microarray highly desirable for application in the diagnosis of patients with multiple congenital defects.

Abnormalities, Multiple↗
PubMed2004

Two novel severe mutations in the pancreatic secretory trypsin inhibitor gene (SPINK1) cause familial and/or hereditary pancreatitis.

Mutations in the serine protease inhibitor Kazal type 1 gene (SPINK1) encoding pancreatic secretory trypsin inhibitor (PSTI) have recently been found to be associated with chronic pancreatitis. Nevertheless, knowledge of severe mutations is particularly scarce, both in terms of number and in the extent of clinical information. The aim of this study was to expand the known spectrum of such mutations. 46 unrelated families, each including at least two pancreatitis patients and carrying neither cationic trypsinogen (PRSS1) mutations nor the frequent SPINK1 N34S mutation, participated in this study. The four exons and their flanking sequences of the SPINK1 gene were screened by denaturing high performance liquid chromatography analysis (DHPLC); and mutations were identified by direct sequencing. A heterozygous microdeletion mutation (c.27delC), which occurs within a symmetric element, was identified in two families. In one family, c.27delC showed segregation with the disease across two generations, with a penetrance of up to 75%. But in the other family, however, the same mutation manifested as a low-penetrance susceptibility factor. In addition, a novel heterozygous splicing mutation, c.87+1G>A (G>A substitution at nucleotide +1 of intron 2) was found in one family with familial pancreatitis. Our results also helped to resolve the sharply differing views about PSTI's role in pancreatitis.

Adult↗
PubMedDate not supplied

Y chromosome deletions in azoospermic men in India.

Genetic factors cause about 10% of male infertility. Azoospermia factors (AZFa, AZFb, AZFc) are considered to be the most important for spermatogenesis. We therefore made an attempt to evaluate the genetic cause of azoospermia, Y chromosome deletion in particular, in Indian men. We have analyzed a total of 570 men, including 340 azoospermic men and 230 normal control subjects. DNA samples were initially screened with 30 sequence-tagged site (STS) markers representing AZF regions (AZFa, AZFb, AZFc). Samples, with deletion in the above regions were mapped by STS walking. Further, the deletions were confirmed by Southern hybridization using the probes from both euchromatic and heterochromatic regions. Of the total 340 azoospermic men analyzed, 29 individuals (8.5%) showed Y chromosome deletion, of which deletion in AZFc region was the most common (82.8%) followed by AZFb (55.2%) and AZFa (24.1%). Microdeletions were observed in AZFa, whereas macrodeletions were observed in AZFb and AZFc regions. Deletion of heterochromatic and azoospermic regions was detected in 20.7% of the azoospermic men. In 7 azoospermic men, deletion was found in more than 8.0 Mb spanning AZFb and AZFc regions. Sequence analysis at the break points on the Y chromosome revealed the presence of L1, ERV, and other retroviral repeat elements. We also identified a approximately 240-kb region consisting of 125 bp tandem repeats predominantly comprised of ERV elements in the AZFb region. Histological study of the testicular tissue of the azoospermic men, who showed Y chromosome deletion, revealed complete absence of germ cells and presence of only Sertoli cells.

Adult↗
PubMedDate not supplied

Reduced human germ cell-less (HGCL) expression in azoospermic men with severe germinal cell impairment.

Germ cell-less (GCL) protein is a nuclear envelope protein highly conserved between the mammalian and Drosophila orthologues. In Drosophila, maternal GCL protein is required to establish the germ lineage during embryonic development. In mammals, it is suggested that the GCL function is mainly in spermatogenesis and that it might be related to the ability of mouse GCL to repress transcription. Using reverse transcriptase-polymerase chain reaction analyses, we investigated the role of human GCL (HGCL) in spermatogenesis by studying its expression in the testicular tissue of 67 azoospermic men with normal karyotype and no Y-chromosome microdeletion. Their testicular biopsy specimens underwent meticulous histological and cytological analysis as well as molecular analysis with various markers of spermatogenesis (RBM1, DAZ, and CDY1). The rate of X-Y and 18 chromosome bivalent formation during meiosis was additionally assessed in 22 of these biopsy specimens and correlated to HGCL expression. Expression of HGCL was affected in parallel with the severity of testicular impairment found. Defective sperm motility was associated with the absence of HGCL. Nevertheless, the absence of HGCL expression did not influence the normal process of chromosome bivalent formation in meiosis. Our results suggest that HGCL is not essential for the chromosomal events of meiosis but might be involved in later aspects of spermatogenesis.

Biopsy↗
PubMedDate not supplied

Phenotypic characteristics of male subfertility and its familial occurrence.

Genetic factors can attribute to male subfertility. A case-control study was carried out to investigate familial occurrence of male subfertility and the phenotypic characteristics of familial male subfertility. The medical data and family histories of 253 severely subfertile men who were candidates for intracytoplasmic sperm injection were compared to the data from 243 randomly selected men. The prevalence of male fertility problems among brothers and maternal uncles of subfertile men was significantly higher than among controls (brothers 10.4% vs 0.5% and maternal uncles 1.7% vs 0.2%). The phenotypes of subfertile men with a positive family history more often showed normal levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) compared to the phenotypes of subfertile men with a negative family history. In addition, subfertile men with a positive family history had a lower percentage of motile sperm. Genetic aberrations, including a chromosomal abnormality or a microdeletion of the Y chromosome, were present in 13.8% of the severely subfertile men. Male subfertility appears to have a familial occurrence, especially among brothers and maternal uncles. Furthermore, examination of the data suggests that subfertile men with a familial occurrence of male subfertility more often have normal levels of FSH and LH and a lower percentage of motile sperm.

Adult↗