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O Raoul

Publications and source records attributed to O Raoul.

At least 19 recordsLinked to original sources
PubMed2006

Array-based comparative genomic hybridisation identifies high frequency of cryptic chromosomal rearrangements in patients with syndromic autism spectrum disorders.

BACKGROUND: Autism spectrum disorders (ASD) refer to a broader group of neurobiological conditions, pervasive developmental disorders. They are characterised by a symptomatic triad associated with qualitative changes in social interactions, defect in communication abilities, and repetitive and stereotyped interests and activities. ASD is prevalent in 1 to 3 per 1000 people. Despite several arguments for a strong genetic contribution, the molecular basis of a most cases remains unexplained. About 5% of patients with autism have a chromosome abnormality visible with cytogenetic methods. The most frequent are 15q11-q13 duplication, 2q37 and 22q13.3 deletions. Many other chromosomal imbalances have been described. However, most of them remain undetectable using routine karyotype analysis, thus impeding diagnosis and genetic counselling. METHODS AND RESULTS: 29 patients presenting with syndromic ASD were investigated using a DNA microarray constructed from large insert clones spaced at approximately 1 Mb intervals across the genome. Eight clinically relevant rearrangements were identified in 8 (27.5%) patients: six deletions and two duplications. Altered segments ranged in size from 1.4 to 16 Mb (2-19 clones). No recurrent abnormality was identified. CONCLUSION: These results clearly show that array comparative genomic hybridisation should be considered to be an essential aspect of the genetic analysis of patients with syndromic ASD. Moreover, besides their importance for diagnosis and genetic counselling, they may allow the delineation of new contiguous gene syndromes associated with ASD. Finally, the detailed molecular analysis of the rearranged regions may pave the way for the identification of new ASD genes.

Adolescent↗
PubMed2005

Molecular cytogenetic analysis of five 2q37 deletions: refining the brachydactyly candidate region.

Deletions of the 2q37 region are associated with a recognizable pattern of MCA/MR so-called the AHO-like syndrome. Brachydactyly is a variable but characteristic feature of this clinical entity. Here we report on five cases of cytogenetically visible de novo deletions of this 2q37 chromosome region. Using FISH, we characterized at the molecular level the breakpoints of these deletions using a set of 15 BACs, PACs and YACs. In four patients, terminal deletions of variable size ranged between 6.2 and 10 Mb. The fifth patient had an interstitial deletion with an AHO-like phenotype including brachydactyly. These findings when compared to previous observations allowed us to narrow down the brachydactyly critical region between BACs RP11-585E12 and RP11-351E10. It contains HDAC4 and STK25 candidate genes loci.

Adult↗
PubMed2004

Genome-wide screening using automated fluorescent genotyping to detect cryptic cytogenetic abnormalities in children with idiopathic syndromic mental retardation.

Mental retardation (MR) is the most common developmental disability, affecting approximately 2% of the population. The causes of MR are diverse and poorly understood, but chromosomal rearrangements account for 4-28% of cases, and duplications/deletions smaller than 5 Mb are known to cause syndromic MR. We have previously developed a strategy based on automated fluorescent microsatellite genotyping to test for telomere integrity. This strategy detected about 10% of cryptic subtelomeric rearrangements in patients with idiopathic syndromic MR. Because telomere screening is a first step toward the goal of analyzing the entire genome for chromosomal rearrangements in MR, we have extended our strategy to 400 markers evenly distributed along the chromosomes to detect interstitial anomalies. Among 97 individuals tested, three anomalies were found: two deletions (one in three siblings) and one parental disomy. These results emphasize the value of a genome-wide microsatellite scan for the detection of interstitial aberrations and demonstrate that automated genotyping is a sensitive method that not only detects small interstitial rearrangements and their parental origin but also provides a unique opportunity to detect uniparental disomies. This study will hopefully contribute to the delineation of new contiguous gene syndromes and the identification of new imprinted regions.

Child↗
PubMed2003

Spectrum of NSD1 mutations in Sotos and Weaver syndromes.

Sotos syndrome is an overgrowth syndrome characterised by pre- and postnatal overgrowth, macrocephaly, advanced bone age, and typical facial features. Weaver syndrome is a closely related condition characterised by a distinctive craniofacial appearance, advanced carpal maturation, widened distal long bones, and camptodactyly. Haploinsufficiency of the NSD1 gene has recently been reported as the major cause of Sotos syndrome while point mutations accounted for a minority of cases. We looked for NSD1 deletions or mutations in 39 patients with childhood overgrowth. The series included typical Sotos patients (23/39), Sotos-like patients (lacking one major criteria, 10/39), and Weaver patients (6/39). We identified NSD1 deletions (6/33) and intragenic mutations (16/33) in Sotos syndrome patients. We also identified NSD1 intragenic mutations in 3/6 Weaver patients. We conclude therefore that NSD1 mutations account for most cases of Sotos syndrome and a significant number of Weaver syndrome cases in our series. Interestingly, mental retardation was consistently more severe in patients with NSD1 deletions. Macrocephaly and facial gestalt but not overgrowth and advanced bone age were consistently observed in Sotos syndrome patients. We suggest therefore considering macrocephaly and facial gestalt as mandatory criteria for the diagnosis of Sotos syndrome and overgrowth and advanced bone age as minor criteria.

Abnormalities, Multiple↗
PubMed2002

Molecular characterization of partial trisomy 16q24.1-qter: clinical report and review of the literature.

We describe a 3(1/2)-year-old girl with psychomotor and mental retardation; dysmorphic features, including a high forehead with bitemporal narrowing; a broad nasal bridge and a broadened nose; downslanting palpebral fissures; abnormal ears; vertebral abnormalities; cardiac defect; genital hypoplasia; and anal abnormalities. The karyotype of our patient (550 bands) was normal. Molecular cytogenetic techniques, including comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH), revealed that this girl was a carrier of a de novo derivative chromosome 7 arising from a cryptic t(7;16)(p22.3;q24.1) translocation generating a trisomy 16q24.1-qter and a 7p22.3-pter deletion. FISH with a series of specific chromosome 7p and 16q probes allowed us to delineate the chromosome 7 breakpoint between YAC660G6 (WD7S517) and YAC848A12 (D7S521, D7S31, and WI-4829) and the chromosome 16 breakpoint between BAC457K7 (D42053) and BAC44201 (SGC30711). The comparison of the clinical features of our patient with those of 2 cases of pure terminal 7p deletion and 28 cases of trisomy 16q reported in the literature allowed us to establish the following phenotype-genotype correlation for trisomy of the long arm of chromosome 16: distinctive facies (high/prominent forehead, bitemporal narrowing, periorbital edema in the neonatal period); severe mental retardation; vertebral, genital, and anal abnormalities to 16q24; distal joint contractures and camptodactyly to 16q23; cleft palate and renal anomalies to 16q22; beaked nose and gall bladder agenesis to 16q21; gut malrotation; lung and liver anomalies to 16q13; and behavior abnormalities to band 16q11-q13.

Abnormalities, Multiple↗
PubMed2002

Automated fluorescent genotyping detects 10% of cryptic subtelomeric rearrangements in idiopathic syndromic mental retardation.

Recent studies have shown that cryptic unbalanced subtelomeric rearrangements contribute to a significant proportion of idiopathic syndromic mental retardation cases. Using a fluorescent genotyping based strategy, we found a 10% rate of cryptic subtelomeric rearrangements in a large series of 150 probands with severe idiopathic syndromic mental retardation and normal RHG-GTG banded karyotype. Fourteen children were found to carry deletions or duplications of one or more chromosome telomeres and two children had uniparental disomy. This study clearly shows that fluorescent genotyping is a sensitive and cost effective method that not only detects cryptic subtelomeric rearrangements but also provides a unique opportunity to detect uniparental disomies. We suggest giving consideration to systematic examination of subtelomeric regions in the diagnostic work up of patients with unexplained syndromic mental retardation.

Child↗
PubMed2001

Comparative genomic hybridisation in mentally retarded patients with dysmorphic features and a normal karyotype.

Segmental aneusomy for small chromosomal regions has been shown to be a common cause of mental retardation and multiple congenital anomalies. A screening method for such chromosome aberrations that are not detected using standard cytogenetic techniques is needed. Recent studies have focused on detection of subtle terminal chromosome aberrations using subtelomeric probes. This approach however excludes significant regions of the genome where submicroscopic rearrangements are also liable to occur. The aim of the present study was to evaluate the efficiency of comparative genomic hybridisation (CGH) for screening of submicroscopic chromosomal rearrangements. CGH was performed in a cohort of 17 patients (14 families) with mental retardation, dysmorphic features and a normal karyotype. Five subtle unbalanced rearrangements were identified in 7 patients. Subsequent FISH studies confirmed these results. Although no interstitial submicroscopic rearrangement was detected in this small series, the study emphasises the value of CGH as a screening approach to detect subtle chromosome rearrangements in mentally retarded patients with dysmorphic features and a normal karyotype.

Cytogenetic Analysis↗
PubMed1995

Proximal deletions of the long arm of the Y chromosome suggest a critical region associated with a specific subset of characteristic Turner stigmata.

Turner syndrome is a complex human disorder that generally associates a 45,X karyotype to a female phenotype presenting with gonadal dysgenesis, short stature and a number of characteristic somatic features. It has been hypothesized that this specific phenotype was the consequence of the haploinsufficiency of some X-linked genes having functional homologs on the Y chromosome. Here we describe four patients with deletions of the long arm of their Y chromosome and presenting with azoospermia and with or without Turner stigmata. Analysis of their breakpoints by Southern blotting and Y-specific sequence tagged sites (STS) allows us to delimit a region located in proximal interval 5 of the Y chromosome involved in skeletal development and growth.

Blotting, Southern↗
PubMed1994

Understanding the mechanism(s) of mosaic trisomy 21 by using DNA polymorphism analysis.

In order to investigate the mechanism(s) underlying mosaicism for trisomy 21, we genotyped 17 families with mosaic trisomy 21 probands, using 28 PCR-detectable DNA polymorphic markers that map in the pericentromeric region and long arm of chromosome 21. The percentage of cells with trisomy 21 in the probands' blood lymphocytes was 6%-94%. There were two classes of autoradiographic results: In class I, a "third allele" of lower intensity was detected in the proband's DNA for at least two chromosome 21 markers. The interpretation of this result was that the proband had inherited three chromosomes 21 after meiotic nondisjunction (NDJ) (trisomy 21 zygote) and subsequently lost one because of mitotic (somatic) error, the lost chromosome 21 being that with the lowest-intensity polymorphic allele. The parental origin and the meiotic stage of NDJ could also be determined. In class II, a "third allele" was never detected. In these cases, the mosaicism probably occurred either by a postzygotic, mitotic error in a normal zygote that followed a normal meiosis (class IIA mechanism); by premeiotic, mitotic NDJ yielding an aneusomic zygote after meiosis, and subsequent mitotic loss (class IIB mechanism); or by a meiosis II error with lack of crossover in the preceding meiosis I, followed by mitotic loss after fertilization (class IIC mechanism). Among class II mechanisms, the most likely is mechanism IIA, while IIC is the least likely. There were 10 cases of class I and 7 cases of class II results.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Segregation of three reciprocal translocations in the same family: t(3;4), t(5;10), and t(15;21).

A male infant with static antenatal encephalopathy and epilepsy was found to have a duplication of 5p12----5pter and deficiency of 10p13----10pter. Each of his parents was a carrier of a balanced reciprocal translocation. A third translocation was found in the maternal grandfather. The pedigree of each translocation and the segregation of parental reciprocal translocations are discussed.

Amino Acids↗
PubMed1992

The meiotic stage of nondisjunction in trisomy 21: determination by using DNA polymorphisms.

We have studied DNA polymorphisms at loci in the pericentromeric region on the long arm of chromosome 21 in 200 families with trisomy 21, in order to determine the meiotic origin of nondisjunction. Maintenance of heterozygosity for parental markers in the individual with trisomy 21 was interpreted as resulting from a meiosis I error, while reduction to homozygosity was attributed to a meiosis II error. Nondisjunction was paternal in 9 cases and was maternal in 188 cases, as reported earlier. Among the 188 maternal cases, nondisjunction occurred in meiosis I in 128 cases and in meiosis II in 38 cases; in 22 cases the DNA markers used were uninformative. Therefore meiosis I was responsible for 77.1% and meiosis II for 22.9% of maternal nondisjunction. Among the 9 paternal nondisjunction cases the error occurred in meiosis I in 2 cases (22.2%) and in meiosis II in 7 (77.8%) cases. Since there was no significant difference in the distribution of maternal ages between maternal I error versus maternal II error, it is unlikely that an error at a particular of maternal ages between maternal I error versus maternal II error, it is unlikely that an error at a particular meiotic stage contributes significantly to the increasing incidence of Down syndrome with advancing maternal age. Although the DNA polymorphisms used were at loci which map close to the centromere, it is likely that rare errors in meiotic-origin assignments may have occurred because of a small number of crossovers between the markers and the centromere.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Gonadotropin responses to low dose pulsatile administration of GnRH in a case of anosmia with hypogonadotropic hypogonadism associated with gonadal dysgenesis 47 XXY.

A 25 year old man presented hypogonadotropic hypogonadism with complete anosmia (Kallman's syndrome). His chromosomic type was 47 XXY (Klinefelter's syndrome). Clinical findings were: height 183 cm, weight 62 kg, increased length of lower limbs, P2-A2 pilosity and micropenis. Only a left testis was present (1.5-1.5 cm). Bone age was 15. Testicular biopsy showed that the signs were more related to the gonadotropic deficit than to the gonadal dysgenesis; tubular hyalinization was not observed. Plasma levels of testosterone and oestradiol were very low. Plasma gonadotropin levels were below normal ranges and did not respond to an infusion test of GnRH. GnRH was administered iv every 90 min for 3 weeks by an auto syringe infusion pump and induced a pulsatile response of FSH and LH. Plasma levels of testosterone and oestradiol were unaffected. It may be concluded that the results of pulsatile injection of GnRH confirmed in this patient a unique association of Kallmann's syndrome with complete 47 XXY Klinefelter's syndrome.

Adult↗
PubMed1986

Coincidence of familial systemic lupus erythematosus and the fragile X syndrome.

The coincidence of fragile X syndrome (fra(X] and systemic lupus erythematosus (SLE) in the same family is reported here for the first time. A 16-year-old boy with typical fra(X) had a severe SLE with multiple organ involvement. His 12-year-old sister of normal intelligence had circulating antinuclear antibodies and proliferative glomerulonephritis. The fra(X) was not found in her karyotype. Except for abnormalities due to immunosuppressive treatment during pregnancy, the association of SLE and chromosome abnormalities has been only reported in Klinefelter's syndrome. The possible pathogenic role of sex hormonal abnormalities due to an extra X chromosome has been suggested in the occurrence of SLE.

Fragile X Syndrome↗
PubMed1985

Cystathionine beta synthase: gene dosage effect in trisomy 21.

The enzymatic activity of cystathionine beta synthase has been studied in fibroblasts of nine patients with regular trisomy 21. An excess of CBS activity was found in trisomy 21 with a trisomy 21/normal ratio equal to 1.66. A 1.04 ratio was found in 21q21----21 p ter monosomy; a 1.04 and 0.99 ratio was found in two 21 qter----21q22.3 monosomies; a 1.14 ratio in 21 qter----21q22 monosomy; a 0.89 ratio in a 21q21----21 pter trisomy; an excess of CBS activity was found in a 21q22.1 ----21q21 trisomy with a 1.57 ratio. These results show a gene dosage effect in human fibroblasts trisomic for chromosome 21 and suggest the assignment of human CBS locus between 21q22.1 and 21q21.

Adolescent↗
PubMed1985

Phenotype-karyotype correlations in dup(18q): report of a case and review.

We report on a case of dup(18q) due to de novo translocation 46,XX,-21,t(18;21)(18qter----cen----21qter). The patient had many characteristic signs of full trisomy 18 except for internal organ malformations and early death. We review the phenotype-karyotype correlations between full trisomy 18 and dup(18q) and discuss the possibility of the existence of "critical zone(s)" at the proximal or/and distal region of 18q responsible for most signs of trisomy 18, such as congenital heart defect and early death.

Abnormalities, Multiple↗