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L Tiepolo

Publications and source records attributed to L Tiepolo.

At least 19 recordsLinked to original sources
PubMed2003

Genetic heterogeneity for a Nijmegen breakage-like syndrome.

Nijmegen breakage syndrome (NBS) is a rare, autosomal-recessive chromosome instability disorder characterized by growth and developmental defects, immunodeficiency, high susceptibility to lymphoid malignancies, hypersensitivity to ionizing radiation and aberrant cell-cycle checkpoint control. The disease is caused by mutations in the NBS1 gene, which encodes nibrin, a component of the hMre11-Rad50-p95 complex involved in cellular response to DNA double-strand breaks. Genetic heterogeneity has been suggested in at least two patients with the NBS phenotype, but no mutation in the NBS1 gene; recently, mutations in the gene encoding the enzyme ligase IV have been identified in patients with signs of NBS. We describe a boy with an NBS clinical phenotype but no mutation in either the NBS1 or the LIG4 genes. The analysis of his cellular phenotype reveals chromosome instability and radiosensitivity, but normal cell-cycle checkpoint control. In addition, a literature review was carried out to summarize and compare data of all NBS-like patients reported to date. This case confirms genetic heterogeneity for NBS. We believe that dissecting the clinical and cellular phenotypes of this and other NBS-like patients will provide useful information for the research of new genes involved in cellular response to DNA damage and the assessment of cancer risk in NBS-like syndrome.

Abnormalities, Multiple↗
PubMed1999

Ring chromosome 9 with a 9p22.3-p24.3 duplication.

UNLABELLED: A ring chromosome 9 containing an inverted 9p22.3-p24.3 duplication was found in a girl presenting with some of the phenotypic characteristics of ring 9 syndrome such as trigonocephaly, microcephaly, hypotelorism, micrognathia, single palmar crease, and bilateral clinodactyly. The typical facial dysmorphic features of 9p duplication, ascribed to trisomy of the band p22, were not present in this patient. Cytogenetic and molecular studies indicated that the duplicated region of band p22 in the ring is confined to the sub-band 22.3. CONCLUSION: The chromosome region responsible for the 9p duplication syndrome appears to be restricted to sub-bands p22. 1-22.2.

Chromosomes, Human, Pair 9↗
PubMed1999

Abnormal methylation does not prevent X inactivation in ICF patients.

DNA undermethylation is a characteristic feature of ICF syndrome and has been implicated in the formation of the juxtacentromeric chromosomal abnormalities of this rare syndrome. We have previously shown that in female ICF patients the inactive X chromosome (Xi) is also undermethylated. This result was unexpected since female ICF patients are not more severely affected than male patients. Here we show that CpG island methylation is abnormal in some ICF patients but in other ICF patients, the difference in methylation pattern between Xi and Xa (active X) is maintained. The consequences of Xi undermethylation on gene expression were investigated by enzyme assays. They showed that significant gene expression did not correlate with CpG island methylation status. The widespread Xi undermethylation does not affect overall Xi replication timing and does not prevent Barr body formation suggesting that a normal methylation pattern is not required for normal chromatin organization of Xi. Molecular investigation of some X-chromosome intron regions showed that the methylation changes in ICF female patients extend to non CpG islands sequences. Our results suggest that the genetic alteration of DNA methylation in ICF syndrome has little consequence on X chromosome gene expression and chromatin organization.

Centromere↗
PubMed1999

Cerebellar dysgenesis and mental retardation associated with a complex chromosome rearrangement.

Cerebellar hypoplasia, mild mental retardation, skeletal abnormalities, and ataxia were present in a 40 years old patient with a complex chromosome rearrangement (CCR). Chromosomes 2, 5, 16, and 17 were involved in the CCR. For the definition of the eight breakpoints leading to the rearrangement FISH with whole chromosomes paintings and specific telomeric probes was employed. Gene disruption, positional effect variegation, and sub-microscopic deletions are all possible causes for the abnormal phenotype observed in the patient.

Adult↗
PubMed1998

Identical de novo mutation at the D4F104S1 locus in monozygotic male twins affected by facioscapulohumeral muscular dystrophy (FSHD) with different clinical expression.

Facioscapulohumeral muscular dystrophy (FSHD) is a progressive hereditary neuromuscular disorder, transmitted in an autosomal dominant fashion. Its clinical expression is highly variable, ranging from almost asymptomatic subjects to wheelchair dependent patients. The molecular defect has been linked to chromosome 4q35 markers and has been related to deletions of tandemly repeated sequences located in the subtelomeric region detected by probe p13E-11 (D4F104S1). We describe a pair of monozygotic male twins affected by FSHD, carrying an identical de novo p13E-11 EcoRI fragment of paternal origin and showing great variability in the clinical expression of the disease, one being almost asymptomatic and the other severely affected. Their medical history was the same, with the exception of an anti-rabies vaccination performed at the age of 5 in the more severely affected twin. We hypothesise that the vaccination might have triggered an inflammatory immune reaction contributing to the more severe phenotype.

Adult↗
PubMed1996

An analysis of Xq deletions.

We characterized by fluorescence in situ hybridization and Southern blotting 14 partial Xq monosomies, 11 due to terminal deletions and 3 secondary to X/autosome translocations. Three cases were mosaics with a XO cell line. In view of the possible role played by telomeres in chromosome segregation, we hypothesize a relationship between the loss of telomeric sequences in terminal deletions and the presence of 45,X cells. A correlation between phenotype and extent of deletion reveal that there is no correspondence between the size of the deletion and impairment of gonadal function. Turner stigmata are absent in patients without an XO cell line, when the breakpoint is distal to Xq24. A low birthweight is present whenever the breakpoint is at q22 or more proximal.

Adolescent↗
PubMed1996

Monosomy of distal 4q does not cause facioscapulohumeral muscular dystrophy.

Facioscapulohumeral muscular dystrophy (FSHD) is a hereditary neuromuscular disorder transmitted in an autosomal dominant fashion. FSHD has been located by linkage analysis in the most distal part of chromosome 4q. The disease is associated with deletions within a 3.2 kb tandem repeat sequence, D4Z4. We have studied a family in which an abnormal chromosome 4 segregates through three generations in phenotypically normal subjects. This chromosome is the derivative of a (4;D or G) (q35;p12) translocation. Molecular analysis of the region 4q35 showed the absence of the segment ranging from the telomere to locus D4F104S1. Probe p13E-11 (D4F104S1), which detects polymorphic EcoRI fragments containing D4Z4, in Southern blot analysis showed only one allele in the carriers of the abnormal chromosome 4. Probe p13E-11 EcoRI fragments are contained in the subtelomeric region of 4q and their rearrangements associated with FSHD suggested that the gene responsible for the muscular dystrophy could be subject to a position effect variegation (PEV) because of its proximity to subtelomeric heterochromatin. The absence of the 4q telomeric region in our phenotypically normal cases indicates that haploinsufficiency of the region containing D4Z4 does not cause FSHD.

Base Sequence↗
PubMed1994

Molecular analysis of a human Y;1 translocation in an azoospermic male.

Cytogenetic studies on an azoospermic male revealed a balanced Y;1 translocation: 46,X,t(Y;1)(q12;p34.3). In situ hybridization with the probe St35-239 (DXY64) and with a probe detecting telomeric sequences revealed that only the Y telomere is involved in the translocation. Fluorescence in situ hybridization with a chromosome 1 library on meiotic preparations revealed consistent contact of the painted chromosome 1 with the sex vesicle at pachytene, the most advanced stage of spermatogenesis observed. No deletions were observed after Southern blot analysis with probes p49f (DYS1), 50f2 (DYS7), and 52d (DYF27), which map in interval 6 of the Y chromosome, which includes the azoospermia factor (AZF) gene. The results indicate that the infertility of the translocation carrier could be due to an alteration of the sex vesicle structure or to a disturbance of X-chromosome inactivation as a result of the proximity to the autosomal portion.

Adult↗
PubMed1992

Interphase cytogenetics of the ICF syndrome.

Interphase behaviour of centromeric heterochromatin of chromosomes 1 and 16 has been investigated in lymphocytes and fibroblasts of patients with ICF syndrome and of normal subjects with non-isotopic in situ hybridization, using the satellite II-related probe pHuR 195. We found evidence for interphase somatic pairing in ICF lymphocytes with a frequency higher than that found in normal cells. Lymphocytes of ICF patients showed nuclear protrusions and micronuclei and these nuclear abnormalities consistently involved a hybridization signal. Somatic pairing was also present in fibroblasts, but with frequencies similar in normal and ICF subjects. The fibroblasts do not have the major chromosomal abnormalities found in lymphocytes. The degree of heterochromatin condensation in fibroblasts was lower than that in lymphocytes and we postulate that the more decondensed state of chromocentres in the fibroblasts could be the reason for the absence of the major chromosomal abnormalities.

Cell Nucleus↗
PubMed1992

A complex chromosome rearrangement with 10 breakpoints: tentative assignment of the locus for Williams syndrome to 4q33----q35.1.

An unbalanced complex chromosome rearrangement with 10 breakpoints resulting in four derivative chromosomes (1, 2, 4, and 11) was found in a girl with severe phenotypic abnormalities, many of which are characteristic of Williams syndrome. The patient was monosomic for the region 4q33----q35.1 and thus the mapping of the syndrome could tentatively be restricted to this region.

Abnormalities, Multiple↗
PubMed1989

Differential expression of the ICF (immunodeficiency, centromeric heterochromatin, facial anomalies) mutation in lymphocytes and fibroblasts.

Fibroblasts from a patient with ICF syndrome were grown in the presence of excess of nucleotides, in media with different amounts of folic acid, and with caffeine in an attempt to induce the chromosomal anomalies observed in lymphocytes. We induced despiralisation and breakages in the centromeric heterochromatin of chromosomes 1 and 16 but not associations and multibranching. We suggest that the absence of the major chromosomal anomalies in fibroblasts from patients with ICF might be the result of both a longer G2 in these cells and differential patterns of interphase heterochromatin associations in the two tissues.

Adenosine↗
PubMed1988

Immunodeficiency, centromeric heterochromatin instability of chromosomes 1, 9, and 16, and facial anomalies: the ICF syndrome.

Instability of the heterochromatic centromeric regions of chromosomes 1, 9, and 16 associated with immunodeficiency was found in a four year old girl. Similar phenotypic and chromosomal abnormalities were described in a previous patient studied by us and in four other published cases. All these patients have facial anomalies in addition to combined immunodeficiency and chromosomal instability. Stretching of the heterochromatic centromeric regions of chromosomes 1, 16, and to a lesser extent, 9 and homologous and non-homologous associations of these regions were the most common cytogenetic findings in all the patients. Multi-branched configurations and whole arm deletions of chromosomes 1 or 16 or both were also found. Comparing clinical and chromosomal data we conclude that immunodeficiency, centromeric heterochromatin instability, and facial anomalies form a new syndrome, for which we propose the acronym ICF. A mutation interfering with the normal process of condensation of part of the centromeric heterochromatin is postulated as the basic chromosome defect in this syndrome.

Child, Preschool↗
PubMed1986

Congenital ocular and other systemic abnormalities associated with ring-11 chromosome.

The ocular and systemic abnormalities in a boy with ring chromosome 11 [46, XY/46, XY, r(11) (p 15.5----q25] are described. The ocular anomalies consisted of bilateral hypermetropia, microcornea, anterior chamber cleavage syndrome with prominent Wölfflin nodes, and cartwheel configuration of the anterior iris leaf. The systemic changes consisted of skeletal, muscular and articular defects, obesity, cryptorchidism, and mild mental retardation.

Abnormalities, Multiple↗
PubMed1982

Agenesis of corpus callosum, ocular, and skeletal anomalies (X-linked dominant Aicardi's syndrome) in a girl with balanced X/3 translocation.

Aicardi's syndrome, which is characterized by agenesis of the corpus callosum, specific chorioretinal abnormalities, and defects of vertebrae and ribs, is considered a probable X-linked dominant trait with male lethality. All features of this syndrome were seen in a girl with a de novo balanced X/3 translocation (46,X,t(X;3)(p22;q12)). It is hypothesized that the clinical picture is the consequence of chromosome breakage within the Aicardi locus. Then, unusual X-inactivation patterns in blood and fibroblasts of this patient can be explained by somatic selection against cells with the Aicardi phenotype.

Abnormalities, Multiple↗
PubMed1981

The "cat eye syndrome": dicentric small marker chromosome probably derived from a no.22 (tetrasomy 22pter to q11) associated with a characteristic phenotype. Report of 11 patients and delineation of the clinical picture.

Eleven patients with the so-called Cat Eye syndrome are reported including a more detailed description of the original cases reported by Schmid and Fraccaro. All cases had, in addition to a normal karyotype, a small extra G-like chromosome which appeared to be an isochromosome for the juxtacentromeric region (pter to q11) of an acrocentric chromosome. None were mosaics. Clinical findings and further cytogenetic studies in a few cases suggest that these markers probably derive from a No. 22 chromosome. Characteristic features of the Cat Eye syndrome in these 11 patients and those reviewed from the literature are: ocular coloboma which may involve the iris, choroid and/or optic nerve, preauricular skin tags and/or pits which are probably the most consistent feature, congenital heart defect, anal atresia with a fistula, renal malformations such as unilateral absence, unilateral or bilateral hypoplasia, and cystic dysplasia, and antimongoloid position of eyes. Intelligence is usually low-normal, although moderate retardation is also seen. There is great variability in the clinical findings ranging from near normal to lethal malformations. Less frequent, but also characteristic findings are: microphthalmia, microtia with atresia of the external auditory canal, intrahepatic or extrahepatic biliary atresia and malrotation of the gut. Direct transmission of the marker from one generation to the other was observed in both sexes. In those families, there was considerable variability in the clinical findings between affected family members. These cases show that there is a bias of ascertainment for patients who have the more striking malformations, especially those with ocular coloboma and anal atresia, a combination which appears to be present in only a minority of cases. Many mildly affected patients probably remain undetected. It is proposed that the term Cat Eye syndrome should be applied only to cases with trisomy or tetrasomy of not more than 22pter to q11 and without additional duplication or deletion of another autosomal segment.

Adolescent↗
PubMed1980

Assignment by deletion mapping of the steroid sulfatase X-linked ichthyosis locus to Xp223.

A male child and his mother who are nullisomic and monosomic, respectively, for the distal portion of Xp because of an unbalanced X-Y translocation were tested for steroid sulfatase activity after clinical examination had yielded evidence for ichthyosis in the boy. Deficiency of steroid sulfatase was found in the male patient, while in his mother enzyme levels were in the heterozygous range. These results, based on cytogenetic evidence obtained with an elongation technique, indicate that the STS locus is at Xp 223.

Adult↗