Chromosome analysis guidelines preliminary report

Knutsen, Turid; Bixenman, Helen; Lawce, Helen J.; Martin, Paulette

doi:10.1016/0165-4608(91)90048-y

Cited by 15 publications

(7 citation statements)

References 1 publication

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“…In 45,XO cases, in which no such abnormality is detected, the possibility of mosaicism should be raised (Koeberl et al, 1995). The number of amniotic cells studied should be increased beyond the 20 metaphases recommended (Knutsen et al, 1991). An additional tissue such as fetal blood could be sampled.…”

Section: Discussionmentioning

confidence: 99%

Are All Phenotypically-Normal Turner Syndrome Fetuses Mosaics?

et al. 1996

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Section: Discussionmentioning

confidence: 99%

Are All Phenotypically-Normal Turner Syndrome Fetuses Mosaics?

et al. 1996

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“…In addition, clinical laboratory genetic testing has undergone various levels of standardization. Such standards, which have been developed by several professional organizations and regulatory agencies, may vary from country to country (Berufsverband Medizinische Genetik, 1990;Knutsen et al, 1990;Hsu et al, 1992;American College of Medical Genetics, 1993;Association of Clinical Cytogeneticists, 1994; EUCROMIC Quality Assessment Group, 1997). Nevertheless, basic guidelines have emerged.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, prenatal cytogenetic testing was introduced into clinical practice with a speed perhaps unmatched by any other invasive testing method. The risk inherent to invasive testing and the consequences of abnormal laboratory results in prenatal, as well as postnatal, testing stipulated the development of guidelines ensuring appropriate counseling of the patient before sampling, the application of appropriate test methods, and control of laboratory techniques (Berufsverband Medizinische Genetik, 1990;Knutsen et al, 1990;Hsu et al, 1992;American College of Medical Genetics, 1993;Association of Clinical Cytogeneticists, 1994;EUCROMIC Quality Assessment Group, 1997). In this paper we describe the development of a nationwide cytogenetic external quality assessment (EQA) scheme in the FRG and its long-term effect on the performance of the participating laboratories.…”

confidence: 99%

The long-term effect of external quality assessment on performance in service cytogenetics

Held¹,

Eiben

Miny

2000

Cytogenet Genome Res

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In 1993 a nationwide cytogenetic external quality assessment program (EQA) was initiated in the Federal Republic of Germany. Presently, some 70 laboratories, representing approximately 90% of all cytogenetic diagnostic tests, are participating in the study. Based on the quality assessment scheme of the Association of Clinical Cytogeneticists (1988) in the United Kingdom, quality of chromosome preparation and speed of routine diagnostic services are being evaluated. As a result of continuous external quality assessment, the mean banding level of participating laboratories rose from below 400 bands per haploid set (bphs) in 1994 to approximately 450 bphs in 1999 in prenatal tests and from about 400 to approximately 500 bphs in postnatal tests over the same 5-yr period. The percentage of participants achieving a banding level of 400 bphs or higher rose from approximately 50% to 93% in prenatal tests and from 60% to 96% in postnatal tests. No significant differences were observed in banding scores achieved by private laboratories compared to university institutes. The impact of the assessment of interpretation, reporting, and documentation remains difficult to evaluate. Preliminary data point to a more stringent adherence to ISCN nomenclature in karyotype designation by participants.

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“…At the time of blood collection, the girl was undergoing physiotherapy and speech therapy; however, the HCL patient had just been diagnosed and interferon therapy was yet to commence. Scoring and analysis Scoring and karyotyping were done according to the guidelines of ISCN (1991) and Knutsen et al (1991).…”

Section: Methodsmentioning

confidence: 99%

Chromosomal 'Puffing' and Undercondensed Segments-additional Indicators of Chromosome Fragility.

Gandhi

Sengupta

et al. 1994

CYTOLOGIA

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Fragile sites, the heritable genomic weak points on the chromosomes which appear as nonstaining gaps of variable width (Sutherland 1979) have been the focus of attention ever since their similarity to the chromosomal breakpoints in disease were reported (Berger et al. 1985, Sutherland and Ledbetter 1989, Trent et al. 1989.As is evident, fragile site expression is affected by a number of specific tissue culture conditions (Fonatsch 1981, Hecht and Glover 1983, Yunis and Soreng 1984. Investigations into the basic mechanism of expression of fragile sites have provided the means for practical demonstration of these sites and at the same time provided some of the clues regarding their molecular structure.High affinity of Distamycin-A and related compounds for binding to d(A) clusters in B-DNA (Hahn 1975) provide a clue to the molecular structure of the fragile sites induced by these compounds. Binding is accompanied by subtle changes in DNA conformation and blocking of the DNA-dependent enzymes (Hahn 1975, Zimmer 1975. On the other hand, both common (Glover et al. 1984) and folate sensitive fragile sites have been proposed to represent stretches of Z-DNA consisting of alternating repeats of poly d(GC/CG) and poly d(AC/TG), which would form single strand lesions when replicating under conditions of limiting dCTP and dTTP.Essentially, the triradial is the most spectacular cytogenetic manifestation of a fragile site, breakage at the site followed by non-disjunction being the mechanism for its production (Noel et al. 1977). This breakage and unequal distribution of the distal fragments may occur repeatedly, giving rise to quadri-radial or even penta-radial figures (Fraccaro et al. 1972. The finding that micronuclei appear more often in individuals with fragile sites than in individuals without them is indicative of the fact that chromosome fragments resulting from breakage at such sites are eliminated by micronuclei formation (Beek et al. 1983).It has been suggested that fragile sites are single stranded gaps resulting from despiraliza tion of DNA due to failure of compact folding in metaphase chromosomes (Taylor and Hagerman 1983). Here, we present certain unique chromosomal features which represent different degrees of undercondensation involving different chromosomes in a case each of hairy cell leukemia and mental retardation. In view of the recent understanding of the role of histone and non-histone proteins, divalent cations and the structural basis of DNA in chromatin packaging, we have tried to explain these features vis-a-vis fragile sites. Material and methodsThe cases being presented in this report include a non-specific mentally retarded girl aged * Technical correspondence.

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Chromosome analysis guidelines preliminary report

Cited by 15 publications

References 1 publication

Are All Phenotypically-Normal Turner Syndrome Fetuses Mosaics?

Are All Phenotypically-Normal Turner Syndrome Fetuses Mosaics?

The long-term effect of external quality assessment on performance in service cytogenetics

Chromosomal 'Puffing' and Undercondensed Segments-additional Indicators of Chromosome Fragility.

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