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PubMed1999

Use of FISH technique in the diagnosis of chromosomal syndromes.

Major chromosome abnormalities are present in 0.65% of all neonates. Fluorescent in situ hybridization (FISH) is useful in diagnosing microdeletion syndromes that would otherwise be difficult to diagnose using standard cytogenetics. In this study, we used FISH analysis in the laboratory diagnosis of 4 patients with Prader-Willi Syndrome [del(15)(q11.2q12)], 4 patients with DiGeorge syndrome [del(22)(q11.2q11.23)] and 4 patients with Williams syndrome [del(7)(q11.23q11.23)]. High-resolution chromosome analysis in all these patients was either normal or inconclusive but all the syndromes were confirmed using FISH. We recommend cytogenetic analysis should always be supplemented with FISH to diagnose all cases suspected of a microdeletion syndrome.

Adolescent↗
PubMedDate not supplied

[Congenital cardiopathies and syndromes in adults].

Among congenital defects the most common are the congenital heart defects, which constitute a heterogeneous group with a multifactor etiology. A single gene mutation has been identified in some of them, such as in of Williams's syndrome, or they can be due to teratogenic agents. The advance in diagnosis and treatment of congenital heart defects has become very important because mortality has diminished and patients live longer and better, reaching adult hood. Molecular biology offers now opportunities understand the cause of many genetic diseases thanks to molecular studies of chromosomes. Conotruncal malformations are known to be caused by a microdeletion in chromosome 22(22q11), this mutation is also responsible for the DiGeorge and cardiovelofacial syndromes, the most relevant aspects are: congenital heart disease, which is present in 75% of the cases, the leading disorder is Fallot's tetralogy with pulmonary atresia, in second place is interruption of the aortic arch type B, followed by common truncus arteriosus. These patients have other phenotypic features, such as high palate, speech problems, malimplantation of ears, and protuberant nose tip, among others. Diagnosis is made with the FISH (fluorescent in situ hybridization) test that shows a microdeletion in chromosome 22 at the 11.2 region. Another syndrome that has received great attention is the Williams-Beuren syndrome, which courses with mental retardation, hypercalcemia, characteristic facies, and supravalvular aortic and pulmonary stenosis. To day, it is known that its cause is a deletion in chromosome 7(7q11.23), which affects elastin region, in consequence, affecting the vessels.

Adult↗
PubMed1999

[Aorto-pulmonary collaterals in an infant with 22q11 monosomy].

The authors present the case of a young girl in whom the diagnosis of pulmonary atresia with ventricular septal defect and multiple aorto-pulmonary collateral vessels was established in the context of microdeletion of chromosome 22. Surgical treatment was excluded following the discovery by angiography of the absence of central pulmonary arteries, a multifocal pulmonary collateral circulation and the appearance of multiple peripheral pulmonary artery stenoses on various aorto-pulmonary collateral vessels during the first months of life. This case illustrates the hypothesis recently developed in the literature according to which the chromosomal abnormality is responsible not only for an anomaly of conotrunkal septation, but also early disorders of branching of the pulmonary vascular bed and disturbances of the connection of peripheral pulmonary segments to central arteries, which are responsible for severe pulmonary vascular abnormalities making biventricular repair of this heart disease in children with 22q11 microdeletion almost always impossible.

Abnormalities, Multiple↗
PubMed2002

The Prader-Willi syndrome and the Angelman syndrome.

The Prader-Willi syndrome and the Angelman syndrome are characterised by a complex clinical and behavioural phenotype resulting from loss of paternal or maternal expression, respectively, of genes located on the human chromosome 15q11-13. Different molecular mechanisms leading to this imbalance have been identified, including microdeletions, intragenic mutations, uniparental disomy and imprinting centre defects. Low copy repeat gene clusters are known to flank the 15q11-13 microdeletion. They predispose to unequal crossing-over events resulting in the deletion. Involvement of multiple disease genes is strongly suspected and traditional positional cloning techniques as well as animal models are used to identify the involved genes. In this review we include the present state of art and a delineation of future approach to study the candidate genes in these two syndromes.

Angelman Syndrome↗
PubMedDate not supplied

[Phenotypic variability of deletion 22q11.2. An analysis of 16 observations with special emphasis on the neurological manifestations].

INTRODUCTION: The microdeletion 22q11.2 affects 1/4000 live births and constitutes the most frequent interstitial chromosomal alteration in humans. It is involved in a heterogeneous series of phenotypic expressions. AIMS: To determine the most important clinical characteristics in a series of patients with this genetic molecular disorder. PATIENTS AND METHODS: We conducted a retrospective study of 16 patients who had been diagnosed, by means of FISH or PCR, as having microdeletion 22q11.2, and the following data were evaluated in a protocolised manner: sex, age, family background, characteristics of the pregnancy, birth, neonatal and post-neonatal periods, clinical and semiological data, as well as the results from the complementary explorations carried out according to the predominant pathology. RESULTS: The age at which the diagnosis was made oscillated between newly born and 8 years, with a predominance of males over females in a ratio of 3.2/1. In all, 81% of patients presented neurological disorders. Brain malformations were seen in six, hypoplasia of the anguli oris muscle in five, congenital facial palsy in three which was associated with brain malformations in one patient, retarded neurodevelopment in six cases and neurogenic arthrogryposis in one. Other findings such as congenital heart disease (75%), skeletal disorders (37%), peculiar phenotypes (31%), nephrourological disorders (19%) and hypoacusis (19%) constitute significant manifestations of the process. Some of the most noteworthy occasional events include retarded height and weight development, hypocalcemia and cleft palate. In one case involving a child whose mother suffered from chronic alcoholism, there were both phenotypic traits of this entity and of foetal alcohol syndrome at the same time. In four of the patients the FISH technique did not detect the deletion, which was confirmed by a technique involving DNA amplification with PCR. CONCLUSIONS: The presence of central and peripheral neurological alterations, together with cardiac, skeletal, renal and auditory disorders was confirmed, as was the existence of neurodevelopmental retardation and a peculiar phenotype. Both the frequency and the kind of disorder coincided with what has been described earlier. A number of facts stand out owing to their novelty. These include the high incidence of asymmetric crying facies, the existence of data compatible with foetal alcohol syndrome in one of the patients with this clinical entity, and the association with neurogenic arthrogryposis in another, which are circumstances that suggest the possibility of a causal relation with the deletion 22q11.2. Using DNA amplification with PCR is seen to be of greater diagnostic efficacy than the FISH technique.

Abnormalities, Multiple↗
PubMedDate not supplied

Congenital cardiac defects with 22q11 deletion.

New cytogenetic techniques have promoted progress in determining the role of chromosomal abnormalities in the cause of congenital cardiac defects. Some patients with congenital cardiac defect have a microdeletion within chromosomal region 22q11, and a majority of them are conotruncal cardiac defects. To determine frequency in our population, we evaluated 36 patients with congenital cardiac defects, 23 of them with conotruncal cardiac defects. Microdeletion of 22q11 was detected in seven of 36 patients (19.4%), and in all deleted cases cardiac pathology was conotruncal.

Abnormalities, Multiple↗
PubMed2003

Molecular markers for diagnosis of Prader-Willi syndrome in thai patients by fish.

Paternal microdeletion of chromosome 15 at q11-q13 has been reported in 75% of Prader-Willi syndrome (PWS) patients in western countries. Diagnosis of PWS in Thailand is mainly based on clinical observation and, in some cases, confirmed by conventional cytogenetic analysis. Loss of a tiny segment in this region (microdeletion) has made it difficult to discriminate from the normal karyotype. An attempt to solve this problem has been made by using a high resolution chromosome culture. However, this method is a tedious and time-consuming technique which is suitable for only experienced cytogeneticists. We report molecular cytogenetic analysis for PWS in Thai patients using FISH in addition to standard GTG- banding chromosome analysis. Nine Thai patients clinically diagnosed or with a suspicion of PWS were investigated. The FISH probes consist of the region-specific probes (SNRPN or D15S10 probe) and two chromosome 15-specific control probes (D15Z1 centromeric and PML chromosome 15 long arm probe). Bright field and FISH programs of an automatic karyotyper were applied to facilitate the efficiency of the chromosome analysis. We found that 2 out of 9 patients showed a deletion at 15q11-q13 region by standard GTG chromosome analysis while 4 out of 9 patients showed a delation in this region by FISH. Consistent losing of SNRPN and D15S10 signals in FISH was observed in these patients. This forty-four per cent deletion is considerably lower than those reported from western countries. We propose that DNA methylation at SNRPN promoter as well as structural abnormalities in other chromosome regions might also play a role in the etiology of this disorder in Thais, which should be investigated further.

Autoantigens↗
PubMed2005

Interstitial loss and gain of sequences on chromosome 22 in meningiomas with normal karyotype.

In nearly half of sporadic low grade meningiomas no chromosome aberration can be detected. In the majority of the other half chromosome 22 is lost. In higher grade meningiomas this loss is followed by characteristic secondary chromosome aberrations. Regarding the molecular findings in Schwannomas, homozygous loss or mutation of the NF2 gene located on chromosome 22, was supposed also to be the primary event in meningioma development. However, in nearly all high grade but in only a minority of low grade meningiomas the loss of the NF2 protein is observed. Therefore, both the hypothetical combined heterozygous loss of or inactivation of two or more tumour suppressor genes (at least one of them located on chromosome 22) or the homozygous loss of a regulatory gene on chromosome 22 different from NF2 was discussed. In search for microdeletions or/and structural recombinations of chromosome 22 we investigated primary cell cultures of 43 meningiomas by conventional G-banding (26 without, 17 with loss of chromosome 22). Twenty-seven tumours were analysed with spectral karyotyping (SKY) and 16 with fluorescence in situ hybridisation (FISH) with DNA probes for the chromosomal regions of 22q11.2, 22q11.23q12.1, 22q12.1 and 22q13.3. SKY analysis confirmed G-banding data for chromosome 22 and could specify marker chromosomes and translocations containing material from chromosome(s) 22. Confirming our assumption microdeletions on chromosome 22 were detected by FISH in 6/8 cytogenetically non-aberrant meningiomas. Surprisingly, in 2/8 cases we observed gains of the 22q13.3 and in 2/8 gains of the 22q12.1 region. Here we present first evidence for an uncommon mechanism during early meningioma development at least for a meningioma subgroup: i) duplication and translocation of sequences from chromosome 22 to different chromosomes. ii) deletion of the original sequences on chromosome 22, resulting in disomy again (only visible as translocation in metaphase FISH). iii) loss of chromosome 22.

Brain Neoplasms↗
PubMedDate not supplied

[Benign idiopathic external hydrocephalus (benign subdural collection) in 39 children: its natural history and relation to familial macrocephaly].

INTRODUCTION: Benign idiopathic external hydrocephalus (BIEH) is an age-dependent disorder that is self-limiting in time and has an uncertain aetiology. PATIENTS AND METHODS: A retrospective study was conducted involving 39 patients (16 girls and 23 boys) with BIEH. The following data were analysed for each patient: age, sex, family history, history concerning pregnancy, childbirth and neonatal period, postnatal history, data from clinical records and from physical examinations, progress of psychomotor development, findings from the first and successive neuroimaging studies, results of other complementary examinations, clinical and neuroimaging situation at the last check-up that was carried out, length of clinical control, age at which subdural effusion disappeared, and any other relevant associated facts. RESULTS: Age at diagnosis ranged from 1.33 and 25 months (mean: 8.4 months); in 38.46% of cases there was a history of macrocephalia in one of the progenitors; in four of them the presence of congenital macrocephalia was noted; in five, there was motor retardation and one of them displayed psychomotor retardation; in 15, there was an association with a slight dilatation of the lateral ventricles; the mean time of clinical control was 3.36 years; the process was seen to resolve in 14 cases; the minimum age for the disappearance of the subdural effusion was 9 months and the maximum was 8 years; macrocephalia persisted until the clinical control ended in 22 of the cases. We also noted the presence of two cases of mitochondrial encephalomyopathy, one craniosynostosis of the sagittal suture, one microdeletion 22q11.2, one a-1 antitrypsin deficiency, and one case of idiopathic bilateral congenital palpebral ptosis. CONCLUSIONS: The subdural effusion and/or macrocephalia persist in a high percentage of these patients and sometimes there is a close relationship between this condition and benign familial macrocephalia. Despite its benignity, it can influence psychomotor or motor retardation and behavioural disorders. On rare occasions it may be associated to mitochondrial encephalomyopathy and to the microdeletion 22q11.2.

Cephalometry↗
PubMed2005

Male infertility: Y-chromosome deletion and testicular aetiology in cases of azoo-/oligospermia.

The spermatogenesis locus azoospermia factor (AZF) in Yq11 has been delineated into three microdeletion intervals designated as AZFa, AZFb andAZFc. AZFc is the most frequently deleted region. We have studied 270 male infertile patients for various genetic disorders associated with infertile phenotype. In this study, we have presented results of our studies on Y-chromosome deletions, chromosomal abnormalities (Klinefelter syndrome) and histology of testis with the objective of seeing whether there were cases of gonosomic mosaicism and a causal correlation between the genetic disorder; and testicular aetiology could be drawn. In all the 13 cases of Y-chromosome microdeletion, AZFc region and DAZ gene were deleted, while no case of AZFa deletion was detected. This result was at variance with other reports from India, where a considerable fraction of cases showed deletion in AZFa region of the Y-chromosome. Both Y-deleted and non-Y-deleted cases revealed heterogeneous testicular phenotype with comparable severity. This disparity among testicular phenotype in cases with known genetic aetiology and even in cases of unknown aetiology can be attributed to different genetic backgrounds and effect of modifiers. Since male infertility is a multifactorial disorder, the contributions of environmental and occupational insults may not be underestimated.

Biopsy↗
PubMed2005

[Epilepsy in three children with Wolf-Hirschhorn syndrome].

OBJECTIVES: Wolf-Hirschhorn syndrome (4p detetion) belongs to the group of disorders caused by chromosomal aberrations, associated with frequent occurrence of epilepsy. To illustrate phenotype - genotype association, the study presents 3 children with this syndrome and epilepsy. MATERIALS AND METHODS: The diagnosis of Wolf-Hirschhorn syndrome was established in 2 patients during neonatal period and in the third child, the 5 month of life. In the majority of patients characteristic phenotype and associated malformations were detected, and the low birth weight and fronto-temporal diameter of the head as well. The structural neuroimaging revealed the diffuse decrease of brain volume without neurodevelopmental malformations. The earliest manifestation of epilepsy was observed in the 4 month old child with 4p. microdeletion as a status epilepticus. In remaining two children with 4p deletion, generalised tonic-clonic seizures were observed for the first time in the 7th month and 7th year, respectively. The standard EEG was performed in infants, while in the 7 year old child a-one-hour videoEEG was recorded. RESULTS: In older children diazepam and clona-zepam were effective to abort seizures, patients became seizure free on carbamazepin and phenobarbital. In the youngest child, status epilepticus being resistant to benzodiazepins, was interrupted with difficulties. Despite generalised type of seizures, EEG revealed focal changes of bioelectrical activity of the brain in two children. In the 7 month old child there were high voltage slow waves in the parieto-temporo-occipital region, while in the 7 year old child videoEEG demonstrated inter-hemispheric asymmetry and asynchrony, and the presence of epileptic grapho-elements, such as spikes and the spike-slow wave complexes as well. CONCLUSION: Epilepsy appeared in children with Wolf-Hirschhorn syndrome with deletion and microdeletion. Status epilepticus in this syndrome may be resistant to benzodiazepins.

Brain↗
PubMed2006

The first Japanese familial Sotos syndrome with a novel mutation of the NSD1 gene.

Sotos syndrome is caused by the haploinsufficiency of the NSD1 gene located in 5q35. More than 70% of the Japanese cases carry microdeletions encompassing of this gene, while point mutations are common in Caucasians. Only 15 familial cases of Sotos syndrome have been reported and all cases shown to have not microdeletions but point mutations. We identified the first Japanese familial case (mother and 3 children). They carry the same mutation at splice donor site of intron 13 (IVS13+1G>A), which results in the in-frame skipping of exon 13. This is also the first familial case caused by the mutation of the splice donor site. Each member of this family showed variable phenotypes and mental development. The present report will contribute to further understanding of genotype-phenotype correlation in Sotos syndrome.

Adult↗
PubMed2006

[Genetic mental retardation].

INTRODUCTION: Mental retardation is a frequently occurring disorder with a major impact on the life of the affected person, the family and society, with an estimated incidence of 1-3% in developed countries. Among the etiologies that cause mental retardation it would appear that 30% have a genetic origin, 15% have an environmental origin, and the rest have an unknown origin. AIM. To report the genetic causes of mental retardation and the new molecular techniques used in order to reach a diagnosis. The identification of the causes of mental retardation is of great interest due to the consequences it has in the intervention, prognosis, estimation of risk of recurrence and its prevention. DEVELOPMENT: Causes of mental retardation are extremely heterogeneous. Genetic causes can be classified as chromosomal alterations (aneuploidies, subtelomeric rearrangements, microdeletion or microduplication syndrome), monogenic, metabolic, or multifactorial alterations. Thanks to the development of high-resolution new techniques -comparative genomic hybridization (CGH) arrays, and multiplex ligation probe amplification (MLPA)- now we are able to detect microdeletions and microduplication all over the genome, which might be related with mental retardation. CONCLUSIONS: The genetic causes of mental retardation are highly heterogeneous and complex. Nowadays and thanks to the new molecular techniques we are able to perform several studies, even though almost half of cases remain undiagnosed. In those undiagnosed cases with positive familial history a genetic counseling can be provided. However, in order to perform a prenatal or a preimplantational study a genetic diagnosis is required.

Chromosome Mapping↗
PubMed1990

Clinical features and molecular analysis of the alpha thalassemia/mental retardation syndromes. I. Cases due to deletions involving chromosome band 16p13.3.

We describe eight patients who have alpha thalassemia which cannot be accounted for by the Mendelian inheritance of abnormal alpha globin genes. Apart from the hematologic abnormality, the other universal clinical finding is mild to moderate mental handicap; there is also a broad spectrum of associated dysmorphic features. Initial analysis of the alpha globin gene complex (which maps to chromosome band 16p13.3), demonstrated that the alpha thalassemia results from failure of the patient to inherit an alpha globin allele from one of the parents. Using a combined molecular and cytogenetic approach, we have extended this analysis to show that all of these patients have 16p deletions which are variable in extent but limited to the terminal band 16p13.3; in at least four cases the deletion results from unbalanced chromosome translocation, and hence aneuploidy of a second chromosome is also present. The relatively nonspecific clinical phenotype contrasts with the other currently known microdeletion syndromes; this may reflect ascertainment bias in the recognition of such syndromes. This work represents the first step in the characterization of a new microdeletion syndrome that is probably underdiagnosed at present.

Adolescent↗
PubMed1994

Isolation and partial characterization of a chloride channel gene which is expressed in kidney and is a candidate for Dent's disease (an X-linked hereditary nephrolithiasis).

Dent's disease, an X-linked renal tubular disorder, is a form of Fanconi syndrome which is characterized by proteinuria, hypercalciuria, nephrocalcinosis, kidney stones and renal failure. Previous studies localised the gene responsible to Xp11.22, within a microdeletion involving the hypervariable locus DXS255. Further analysis using new probes which flank this locus indicate that the deletion is less than 515 kb. A 185 kb YAC containing DXS255 was used to screen a cDNA library from adult kidney in order to isolate coding sequences falling within the deleted region which may be implicated in the disease aetiology. We identified two clones which are evolutionarily conserved, and detect a 9.5 kb transcript which is expressed predominantly in the kidney. Sequence analysis of 780 bp of ORF from the clones suggests that the identified gene, termed hCIC-K2, encodes a new member of the CIC family of voltage-gated chloride channels. Genomic fragments detected by the cDNA clones are completely absent in patients who have an associated microdeletion. On the basis of the expression pattern, proposed function and deletion mapping, hCIC-K2 is a strong candidate for Dent's disease.

Amino Acid Sequence↗
PubMed1995

Racial disparity in the association of p53 gene alterations with breast cancer survival.

A significant black/white difference in breast cancer prognosis has been observed in the United States. Alterations of p53 tumor suppressor gene in breast cancer have been associated with poor prognosis. This study was designed to test the hypothesis that p53 gene alterations are related to the difference in prognosis between black and white breast cancer patients. Formalin-fixed paraffin-embedded breast tissue blocks were available from 45 black and 47 white patients for PCR-single strand conformation polymorphism analysis and DNA sequencing. The types of p53 gene alterations were compared between blacks and whites. Associations between p53 gene alterations and survival were also evaluated. Three missense, 2 nonsense, 1 microdeletion, 1 intron, and 4 silent mutations were detected in blacks, while 7 missense, 1 microdeletion, 1 silent mutation, and 3 polymorphisms were observed in whites. Among the point mutations, G:C to A:T transitions at non-CpG sites were found in 80.0% of blacks (8 of 10) and 62.5% of whites (5 of 8). Significantly poorer survival associated with p53 gene alterations was observed for blacks (P = 0.012), but not for whites. Black patients with p53 alterations had a significant 4-5-fold excess risk of death from breast cancer than those without p53 alterations. Adjustment for stage, age, tumor histopathology, receptor status, and adjuvant treatment did not change the excess risk. The findings suggest that the types of p53 gene alterations may contribute to the racial difference in breast cancer survival.

Adult↗
PubMed1996

[Genetics of hereditary cardiopathies].

Hypertrophic cardiomyopathy may be secondary to a mutation in the cardiac beta myosin heavy chain (14q11-q12), alpha tropomyosin (15q22), troponin T (1q32), protein C gene (11p11-q13) or in a non yet mapped gene. A X-linked dilated cardiomyopathy may be due to a mutation in the dystrophin gene (Xp21). The long QT syndrome may be secondary to a mutation in a potassium channel (7q35-36), an alpha subunit of the sodium channel gene (3p21) or in genes not yet identified (11p15.5, 4q25-q27). Marfan syndrome is associated to mutations in the fibrillin 1 gene (15q21.1) and a Marfan-like syndrome with not ocular anomalies was mapped to 3p24. Patients with Williams-Beuren syndrome have microdeletions in 7q11, whereas in the supravalvular aortic stenosis, the elastin gene which maps to the same region, is mutated. In Di George and Shprintzen syndromes but not in conotruncal malformations, microdeletions in 22q11 are observed. Heterotaxia can be transmitted by 3 types of mendelian inheritance (Xq24-q27.1). Finally, other diseases were mapped: Noonan and Holt-Oram syndromes (12q), isolated conduction blocks (19q13.3), arrhythmogenic right ventricular cardiomyopathy (14q23-q24), total anomalous pulmonary venous return (4p13-q12) and Osler-Weber-Rendu (9q33-q34.1, 3p22 and 12q1). In the near future, these incoming data will deeply modify the cardiovascular field.

Abnormalities, Multiple↗
PubMed1997

Microsatellite DNA markers detects 95% of chromosome 22q11 deletions.

Cono-truncal cardiac malformations account for some 50% of congenital heart defects in newborn infants. Recently, hemizygosity for chromosome 22q11.2 was reported in patients with the DiGeorge/Velo-cardio-facial syndromes (DGS/VCFS) and causally related disorders. We have explored the potential use of microsatellite DNA markers for rapid detection of 22q11 deletions in 19 newborn infants referred for cono-truncal heart malformations with associated DGS/VCFS anomalies. A failure of parental inheritance was documented in 84.2% of cases (16/19). PCR-based genotyping using microsatellite DNA markers located within the commonly deleted region allowed us either to confirm or reject a 22q11 microdeletion in 94.3% of cases (18/19) within 24 hours. This test is now currently performed in the infants referred to us for a cono-truncal heart malformation as a first intention screening for 22q11 microdeletion.

Alleles↗