1/1542. Increased sister chromatid exchange in bone marrow and blood cells from Bloom's syndrome.Bone-marrow cells from a patient with Bloom's syndrome cultured for 48 h in the presence of BudR exhibited a striking increase in the number of sister chromatid exchanges (SCEs) in comparison to that in the marrow cells of a patient with treated polycythemia vera (PV). Thus, it appears that an increased incidence of SCE in Bloom's syndrome occurs in various differentiated types of cells, not just blood lymphocytes, and constitutes the syndrome's most characteristic cytogenetic feature. In contrast, the incidence of SCE was not increased in marrow cells and lymphocytes of the particular PV patient studied here, whose cells did exhibit increased numbers of chromatid and chromosome gaps and breaks, presumably as result of the patient's earlier treatment. An increased frequency of SCE was demonstrated in Bloom's syndrome lymphocytes using both a technique based on BudR incorporation and one based on labeling with tritated deoxycytidine. This observation constitutes evidence against the increase of SCE being due to an unusual reaction to BudR. By conventional cytogenetic techniques, chromosome instability, including chromatid and chromosome breaks, but no homologous chromatid interchanges were also recognized in Bloom's syndrome bone-marrow cells incubated in vitro (without BudR) for either 1.k or 16 h. This observation points to the existence of chromosome instability in vivo.- - - - - - - - - - ranking = 1keywords = chromosome (Clic here for more details about this article) |
2/1542. Phenotypic variability in the chromosome 9 ring.The syndrome associated to the 9 ring is not commonly observed. The first remark was by Kistenmacher (1970) who examined a male. Later observation of other cases has allowed the syndrome to be described, so that it can be said to be characterized by constant signs, such as microcephaly, psychomotor retardation of varying entity and facial dysmorphism corresponding to that observed in 9 p monosomy. The variability of the phenotype has to be compared with the entity of the telomeric deletion, since the clinical outlook, especially the entity of retardation, could be less serious in case of small deletions.- - - - - - - - - - ranking = 1keywords = chromosome (Clic here for more details about this article) |
3/1542. Genetic analysis of three patients with an 18p- syndrome and dystonia.Some patients with an 18p- syndrome show dystonia, and a focal dystonia gene has been mapped to chromosome 18p. The authors evaluated the extent of the deletion in three patients with an 18p- syndrome and dystonia using 14 dna markers on 18p. A common deleted area, covering the DYT7 locus, places the putative dystonia gene between the telomere of 18p and D18S1104 (49.6 cM). dystonia in these patients may be caused by haploinsufficiency of the DYT7 gene, a new dystonia gene on 18p, or may result from developmental brain anomalies.- - - - - - - - - - ranking = 0.25keywords = chromosome (Clic here for more details about this article) |
4/1542. ataxia, ocular telangiectasia, chromosome instability, and Langerhans cell histiocytosis in a patient with an unknown breakage syndrome.An 8 year old boy who had Langerhans cell histiocytosis when he was 15 months old showed psychomotor regression from the age of 2 years. microcephaly, severe growth deficiency, and ocular telangiectasia were also evident. Magnetic nuclear resonance imaging showed cerebellar atrophy. Alphafetoprotein was increased. Chromosome instability after x irradiation and rearrangements involving chromosome 7 were found. Molecular study failed to show mutations involving the ataxia-telangiectasia gene. This patient has a clinical picture which is difficult to relate to a known breakage syndrome. Also, the relationship between the clinical phenotype and histiocytosis is unclear.- - - - - - - - - - ranking = 1.25keywords = chromosome (Clic here for more details about this article) |
5/1542. monosomy 18q syndrome and atypical rett syndrome in a girl with an interstitial deletion (18)(q21.1q22.3).We describe a 6 1/2-year-old girl with an interstitial deletion of chromosome arm 18q (18q21.1q22.3). Her clinical manifestations are a combination of those found in monosomy 18q syndrome and those of rett syndrome. cytogenetic analysis demonstrated a deletion of the long arm of chromosome 18, defined by molecular analysis with polymorphic markers as a de novo interstitial deletion, paternally derived. The findings typical of the 18q- syndrome included mental retardation, midface hypoplasia, and hypoplasia of labia majora, and those typical of rett syndrome were severe mental retardation, autistic behavior, inappropriate hand-washing movements, epilepsy, attacks of sighing and hyperventilation, and progressive scoliosis since the age of 5 years. She did not have microcephaly, and the mental delay was obvious from an early age without a period of normal development, which makes the diagnosis of rett syndrome atypical. Previously, a girl with mosaicism for a monosomy 18q associated with rett syndrome has been described. That girl had a terminal deletion of chromosome 18q, which seems to coincide in part with that in the present girl. It is possible that genes in the distal region of 18q are involved in the etiology of rett syndrome.- - - - - - - - - - ranking = 0.75keywords = chromosome (Clic here for more details about this article) |
6/1542. Kenny-Caffey syndrome: an Arab variant?We describe 2 unrelated Bedouin girls who met the criteria for the diagnosis of Kenny-Caffey syndrome. The girls had some unusual features--microcephaly and psychomotor retardation--that distinguish the Kenny-Caffey syndrome profile in Arab children from the classical Kenny-Caffey syndrome phenotype characterized by macrocephaly and normal intelligence. The 2 girls did not harbor the 22q11 microdeletion (the hallmark of the DiGeorge cluster of diseases) that we previously reported in another Bedouin family with the Kenny-Caffey syndrome (Sabry et al. J Med Genet 1998: 35(1): 31-36). This indicates considerable genetic heterogeneity for this syndrome. We also review previously reported 44 Arab/Bedouin patients with the same profile of hypoparathyroidism, short stature, seizures, mental retardation and microcephaly. Our results suggest that these patients represent an Arab variant of Kenny-Caffey syndrome with characteristic microcephaly and psychomotor retardation. We suggest that all patients with Kenny-Caffey syndrome should be investigated for the 22q11 microdeletion. Other possible genetic causes for the Kenny-Caffey syndrome or its Arab variant include chromosome 10p abnormalities.- - - - - - - - - - ranking = 0.25keywords = chromosome (Clic here for more details about this article) |
7/1542. Fibroblast growth factor homologous factor 2 (FHF2): gene structure, expression and mapping to the Borjeson-Forssman-Lehmann syndrome region in Xq26 delineated by a duplication breakpoint in a BFLS-like patient.Borjeson-Forssman-Lehmann syndrome (BFLS) is a syndromal X-linked mental retardation, which maps by linkage to the q26 region of the human x chromosome. We have identified a male patient with BFLS-like features and a duplication, 46,Y,dup(X)(q26q28), inherited from his phenotypically normal mother. fluorescence in situ hybridisation using yeast artificial chromosome clones from Xq26 localised the duplication breakpoint to an approximately 400-kb interval in the Xq26.3 region between DXS155 and DXS294/DXS730. database searches and analysis of available genomic dna sequence from the region revealed the presence of the fibroblast growth factor homologous factor gene, FHF2, within the duplication breakpoint interval. The gene structure of FHF2 was determined and two new exons were identified, including a new 5' end exon, 1B. FHF2 is a large gene extending over approximately 200 kb in Xq26.3 and is composed of at least seven exons. It shows tissue-specific alternative splicing and alternative transcription starts. Northern blot hybridisation showed highest expression in brain and skeletal muscle. The FHF2 gene localisation and tissue-specific expression pattern suggest it to be a candidate gene for familial cases of the BFLS syndrome and other syndromal and non-specific forms of X-linked mental retardation mapping to the region.- - - - - - - - - - ranking = 0.5keywords = chromosome (Clic here for more details about this article) |
8/1542. Delineation of two distinct 6p deletion syndromes.Deletions of the short arm of chromosome 6 are relatively rare, the main features being developmental delay, craniofacial malformations, hypotonia, and defects of the heart and kidney, with hydrocephalus and eye abnormalities occurring in some instances. We present the molecular cytogenetic investigation of six cases with 6p deletions and two cases with unbalanced translocations resulting in monosomy of the distal part of 6p. The breakpoints of the deletions have been determined accurately by using 55 well-mapped probes and fluorescence in situ hybridization (FISH). The cases can be grouped into two distinct categories: interstitial deletions within the 6p22-p24 segment and terminal deletions within the 6p24-pter segment. Characteristics correlating with specific regions are: short neck, clinodactyly or syndactyly, brain, heart and kidney defects with deletions within 6p23-p24; and corneal opacities/iris coloboma/Rieger anomaly, hypertelorism and deafness with deletions of 6p25. The two cases with unbalanced translocations presented with a Larsen-like syndrome including some characteristics of the 6p deletion syndrome, which can be explained by the deletion of 6p25. Such investigation of cytogenetic abnormalities of 6p using FISH techniques and a defined set of probes will allow a direct comparison of reported cases and enable more accurate diagnosis as well as prognosis in patients with 6p deletions.- - - - - - - - - - ranking = 0.25keywords = chromosome (Clic here for more details about this article) |
9/1542. Splenic syndrome in sickle cell trait: four case presentations and a review of the literature.Four cases of splenic infarction/sequestration in sickle cell trait (SCT) patients are presented. All four patients were undergoing moderate exercise at elevations ranging from 5,500 to 12,000 feet. The patients include two African-American males, a Hispanic male, and a white female. All four presented with the acute onset of mid epigastric then left upper-quadrant pain, nausea, vomiting, and respiratory splinting. A review of the literature indicates that splenic infarction with SCT is not uncommon; however, not surprisingly, it is often initially misdiagnosed. This is the first report in the literature of a female with SCT incurring a splenic syndrome with exposure to terrestrial altitude. Although SCT is not a contraindication for moderate- or high-altitude activities, military physicians need to consider the diagnosis of splenic infarction early in any patient regardless of race or sex who presents with left upper-quadrant pain at altitudes above 5,000 feet. Prompt evacuation to sea level may hasten recovery and spare further splenic trauma. Although SCT should be considered a relatively benign entity, the literature also suggests a higher than average risk of sudden death in military recruits with SCT from exertional heat illness and rhabdomyolysis.- - - - - - - - - - ranking = 0.0015397691257237keywords = sex (Clic here for more details about this article) |
10/1542. The same mutation affecting the splicing of WT1 gene is present on frasier syndrome patients with or without Wilms' tumor.Denys-Drash and Frasier syndromes are rare human disorders that associate nephropathy with gonadal and genital abnormalities. In DDS there is a predisposition to Wilms' tumor. Heterozygous point mutations in the Wilms' tumor, type1 gene (WT1), particularly those altering the zinc finger (ZF) encoding exons, have been reported in most DDS patients, while mutations in intron 9 of the same gene cause FS. This paper describes two cases of DDS, one FS and one patient with Wilm's tumor and intersex genitalia, in which mutations were searched by sequencing the exons 8 and 9 of WT1 gene. Patient 1 carried a missense point mutation in exon 8 (ZF2), converting a CGA-Arg codon to a TGA-stop codon. Patient 2 presented a single nucleotide deletion within exon 9 (ZF3) introducing a premature chain termination at codon 398. patients 3 and 4 had a C-->T transition at position 4 of the second alternative splice donor site of exon 9 (this mutation was detected in peripheral blood and in tumor derived dna of patient 3). However, patient 3 had previously developed a Wilms' tumor. This is the first case of Wilms' tumor development in a phenotypically and genetically confirmed case of FS.- - - - - - - - - - ranking = 0.0015397691257237keywords = sex (Clic here for more details about this article) |
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