Biomedical subjects
Publications and source records attributed to P Maraschio.
Cytogenetic analysis in a male child with dismorphies and renal anomalies showed an extra bisatellited chromosome. In situ hybridization and an analysis of cytogenetic polymorphisms revealed that the abnormal chromosome derived from a single maternal chromosome 22.
Cytogenetic analysis of two pancreatic islet tumors, an insulinoma and a glucagonoma was ascertained in two subjects with multiple endocrine neoplasia type 1 (MEN1). The insulinoma had a modal peak at 84 chromosomes. Most cells were pseudotetraploid, and in all cells the normal chromosomes were represented in varied numbers, i.e., from 1 to 7 copies. The tumor had 5 characteristic and consistent marker chromosomes which were identified as deletions of chromosomes 1, 2, 7, 16, and 17. All metaphases had several double minute chromosomes (dmin) of variable size and possible intermediate structures between dmin and homogeneously staining chromosomal regions. The glucagonoma had a nearly equal proportion of normal metaphases and metaphases with structural and numerical abnormalities with no consistent trend.
In short-term cultures of tumor tissue from a medullary thyroid carcinoma (MTC), we found a large clone of cells with a balanced translocation t(9;12)(p24;q22). A large clone with a balanced translocation t(10;16)(p11;q24) was also found in cultures from a C-cell thyroid hyperplasia. No clearcut evidence for chromosome instability was observed in the lymphocytes of the two patients. The mother of the first patient died of MTC; two relatives of the second patient had MTC and one of them had pheochromocytoma. These findings classify the two subjects as MEN 2A patients with different phenotypic expression but with the same type of chromosomal abnormality.
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.
The parental origin of the de novo deleted chromosome 4 was studied in five cases of Wolf-Hirschhorn syndrome using polymorphic probes mapping in the 4p16.3 region. In all the patients the deleted chromosome was found to be of paternal origin and these results, together with similar ones obtained by another group, make the preferential paternal origin of the de novo chromosome 4 deletion highly significant.
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.
The X-linked NFE1 gene encodes an erythroid factor involved in globin gene transcription. Using a human cDNA clone encoding this factor, we show, by in situ hybridization and by analysis of human-rodent hybrid cell lines, that this gene is located in Xp11.23. In the absence of polymorphisms in the NFE1 gene, these results allow the study of the possible relationships between NFE1 mutations and X-linked hereditary persistence of fetal hemoglobin by linkage analysis with RFLP markers of the region. A female patient, hemizygous for the NFE1 locus, shows essentially normal hematological parameters.
A consistent degree of chromosome instability was found in cultured lymphocytes and in fibroblasts derived from skin biopsies of three patients with multiple endocrine neoplasia type 1 (MEN1). In both tissues, there was a significant increase in chromosomal breakage. Dicentrics and tricentrics, rings, translocations, deletions, acentric fragments, and presumptive double minutes were the most frequent abnormalities in lymphocytes. The fibroblasts of two patients had large clones consisting of trisomy 7 and trisomy 18 cells, respectively.
Short stature is consistently found in individuals with terminal deletions of Xp. In order to refine the localization of a putative locus affecting height, we analyzed two patients with a partial monosomy of the pseudoautosomal region at the molecular level. Eight pseudoautosomal probes were used for the genetic deletion analysis through dose evaluation. Three of them represent new markers (DXS415, DXS419, and DXS406) which were positioned on the pseudoautosomal map by pulsed field gel electrophoresis. Our data suggest that a locus affecting height maps in a region of about 1.5 Mbp, distal to the DXS406 locus and proximal to the DXS415 locus, a region which includes two CpG islands, and rule out an involvement of very distal sequences at the X/Y telomeres.
Stable dicentric chromosomes behave as monocentrics because one of the centromeres is inactive. The cause of centromere inactivation is unknown; changes in centromere chromatin conformation and loss of centromeric DNA elements have been proposed as possible mechanisms. We studied the phenomenon of inactivation in two Y centromeres, having as a control genetically identical active Y centromeres. The two cases have the following karyotypes: 45, X/46,X,i(Y)(q12) and 46,XY/47,XY,+t(X;Y) (p22.3;p11.3). The analysis of the behavior of the active and inactive Y chromosome centromeres after Da-Dapi staining, CREST immunofluorescence, and in situ hybridization with centromeric probes leads us to conclude that, in the case of the isochromosome, a true deletion of centromeric chromatin is responsible for its stability, whereas in the second case, stability for its stability, whereas in the second case, stability of the dicentric (X;Y) is the result of centromere chromatin modification.
A severely retarded and dysmorphic girl, carrying an unbalanced X/7 translocation with breakpoints at Xq28 and 7p14, was analyzed by cytogenetic, biochemical and molecular techniques. The X/7 translocated chromosome was found to replicate consistently late in the 105 metaphases analyzed. In 83 of these cells, late replication was limited to the X portion of the abnormal chromosome, whereas in 22 cells incomplete spreading into the autosomal fragment was observed. Southern blot and in situ hybridization experiments with probe G80 (locus D7S373) (previously localized to 7p13-15) and G98 (localized to 7p14-15) assigns the former to 7p15 and the latter to 7p14, thus suggesting the order 7ter-G80-G98-cen. The activity of the enzyme phosphoserine phosphatase localized to 7pter-p14 was increased. Southern blotting experiments with 19 probes spanning the entire X chromosome demonstrated that the translocated chromosome had lost a portion of Xq28 (locus DXS51) but still retained part of Xq27 (F9 locus). The results confirm that the proband is trisomic for the region 7p15-pter and monosomic for the region Xq28-qter. Comparing her phenotype with those of other cases of partial trisomy or monosomy 7p, we confirm that band 7q21 is probably involved in skull development.
Two cases of 47,XXX males were studied, one of which has been published previously (Bigozzi et al. 1980). Analysis of X-linked restriction fragment length polymorphisms revealed that in this case, one X chromosome was of paternal and two were of maternal origin, whereas in the other case, two X chromosomes were of paternal and one of maternal origin. Southern blot analysis with Y-specific DNA probes demonstrated the presence of Y short arm sequences in both XXX males. In one case, the results obtained pointed to a paracentric inversion on Yp of the patient's father. In situ hybridization indicated that the Y-specific DNA sequences were localized on Xp22.3 in one of the three X chromosomes in both cases. The presence of Y DNA had no effect on random X inactivation. It is concluded that both XXX males originate from aberrant X-Y interchange during paternal meiosis, with coincident nondisjunction of the X chromosome during maternal meiosis in case 1, and during paternal meiosis II in case 2.
Normal levels of adenylate kinase (AK-1) and of alpha 1-acid glycoprotein (ORM1) were found in a girl with a deletion 9q32-qter secondary to a maternal translocation (4q35; 9q32), thus excluding these loci from the deleted region. These results, and comparison with other informative data, map the locus for AK-1 to 9q32 and that for ORM1 to region 9q31-q32. The girl has several signs of the Goltz syndrome (Focal dermal hypoplasia), which is listed in the McKusick catalog (no. 30560) as an X-linked dominant condition. Our finding indicates that the locus for Golz syndrome is autosomal and in region 9q32-qter or that there are two such conditions, one autosomal and one X-linked.
Male and female sibs born to third-cousin parents presented with mental retardation, microcephaly, short stature, juvenile onset limb-girdle muscular dystrophy and multiple chromosome mosaicism in lymphocytes and fibroblasts. Different aneuploidies (mostly trisomies) were found in 15-20% of the cells and trisomies for chromosome 8 and chromosome 7 predominated in lymphocytes and fibroblasts respectively, while monosomies were rare. Increased cellular death due to aneuploidy could explain symptoms such as mental and growth retardation and microcephaly. This could be an instance of an autosomal recessive mitotic mutant, possibly affecting a protein simultaneously involved in spindle apparatus and muscle function.
A 13 year old male with a severe progressive neurological disorder was found to have a pseudodicentric chromosome resulting from a telomeric fusion 15p;20p. In lymphocytes, the centromeric constriction of the abnormal chromosome was always that of the chromosome 20, while in fibroblasts both centromeres were alternately constricted. Cd staining was positive only at the active centromere, but a weak anticentromere immunofluorescence was present at the inactive one. We suggest that centromere inactivation results from a modified conformation of the functional DNA sequences preventing normal binding to centromere specific proteins. We also postulate that the patient's disorder, reminiscent of a spongy glioneuronal dystrophy as seen in Alper's and Creutzfeldt-Jakob diseases, may be secondary to the presence of the pathogenic isoform of the prion protein encoded by a gene mapped to 20p12----pter.
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.
A complex balanced three-break-point rearrangement between chromosome 2 and chromosome 7 and a balanced reciprocal translocation between chromosome 5 and chromosome 20, were found associated in a girl and in her mother and grandmother. All three of them have microcephaly, low stature, peculiar asymmetric facies and slight mental retardation. We postulate that one (or more) of the five chromosome break-points disrupted one (or more) gene, leading to the expression of the syndrome and to its segregation with the chromosome rearrangement in three generation. Our finding confirms the efficiency of balanced translocations for gene mapping, althought it has led only to the exclusion mapping of all chromosomes except 2, 5, 7 and 20.
We have isolated a human DNA fragment (laboratory acronym G98) that detects related sequences in mammals, chicken and Drosophila DNAs. This sequence has been mapped to human chromosome 7 p14-p15 by in situ hybridization. Probe G98 recognizes an insertion-deletion type polymorphism, with allelic frequencies of about 0.5, which can be detected with at least six different restriction enzymes. A second polymorphism, which can be detected in human DNA digested with TaqI, is in non-complete linkage disequilibrium with the first polymorphism. About 70% of the individuals analysed have been found to be heterozygous at this locus.