Quinacrine fluorescence of metaphase chromosomes. Identical patterns in different tissues

Sex chromosome markers: characterization using fluorescence in situ hybridization and review of the literature

Fluorescence in situ hybridization (FISH) using biotin labeled X- and Y-chromosome DNA probes was utilized in the analysis of 23 sex chromosome-derived markers. Specimens were obtained through prenatal diagnosis, because of a presumptive diagnosis of Ullrich-Turner syndrome, mental retardation, and minor anomalies or ambiguous genitalia; three were spontaneous abortuses. Twelve markers were derived from the X chromosome and eleven from the Y chromosome; this demonstrates successfully the value and necessity of FISH utilizing DNA probes in the identification of sex chromosome markers. Both fresh and older slides, some of which had been previously G-banded, were used in these determinations. We have also reviewed the literature on sex chromosome markers identified using FISH.

Hemoglobin S/hemoglobin Osler: a case with 3 beta globin chains. DNA sequence (AAT) proves that Hb Osler is beta 145 Tyr-->Asn

A 13-year-old African-American female with erythrocytosis and three different beta globins on electrophoresis beta A, beta S, and beta Osler, raised the possibility that one chromosome 11 might contain a duplicated beta globin gene, since there are normally only 2 beta globin genes. DNA sequence analysis showed GTG at codon 6 in exon 1, corresponding to Hb S and AAT at codon 145 in exon 3, indicating a substitution of Asn for Tyr. Thus, Hb Osler undergoes spontaneous post-translational deamidation, beta 145 Asn-->beta 145 Asp. Unmodified Hb Osler (Asn) co-migrates with Hb A on electrophoresis and co-elutes with Hb A on HPLC; therefore it has not been identified previously. All previous studies have incorrectly identified the mutation as being beta 145 (HC 2) Tyr-->Asp.

Early studies on human chromosomes

The author describes his introduction to the field of cytogenetics, with his first viewing of himself, cytogenetically, down the microscope, and the progression of human cytogenetics as an area of study up to its modern integration with molecular genetics and computer technology.

Idarubicin in combination with cytarabine and VP-16 in the treatment of post myelodysplastic syndrome acute myeloblastic leukemia (MDS-AML)

Fifteen patients with a primary myelodysplastic syndrome (MDS) transformed into acute myeloblastic leukemia (AML) were treated with an intensive chemotherapy regimen containing idarubicin. A complete response (CR) was obtained in 10 patients (66.6%). In five of them this was achieved after a single course of chemotherapy. The median time to achieve a CR was 32 days (range 16-42). A partial remission (PR) was obtained in 2 patients after two induction courses of chemotherapy. One patient died during the first induction course following acute respiratory distress syndrome (ARDS) complication, whereas the chemotherapy regimen failed in 2 patients. A short interval between MDS and transformation into AML was associated with a better chance of achieving a CR. Age, karyotype, type of MDS, peripheral blood or bone marrow findings appeared to have no influence on the response to treatment. The median event free survival for patients who achieved CR was 15 months and the median actuarial survival 18 months. These preliminary results need to be confirmed in a multicentre prospective study comparing idarubicin with other anthracyclines.

Medical genetics

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An improved technique for sequential R-, Q- and C-banding of bone marrow chromosomes

A procedure for the sequential staining of metaphase cells to provide R-banding, Q-banding and C-banding of chromosomes is described. The combined techniques allow more precise identification of marker chromosomes and more accurate definition of breakpoints in the consistent chromosome translocations that are associated with certain human malignancies.