A case of acute myeloid leukemia (AML) with an unreported combination of chromosomal abnormalities: gain of isochromosome 5p, tetrasomy 8 and unbalanced translocation der(19)t(17;19)(q23;p13)

BACKGROUND

Acute myeloid leukemia (AML) comprises a spectrum of myeloid malignancies which are often associated with distinct chromosomal abnormalities, and the analysis of such abnormalities provides us with important information for disease classification, treatment selection and prognosis. Some chromosomal abnormalities albeit recurrent are rare such as tetrasomy 8 or isochromosome 5p. In addition, erratic chromosomal rearrangements may occur in AML, sometimes unbalanced and also accompanied by other abnormalities. Knowledge on the contribution of rare abnormalities to AML disease, progression and prognosis is limited.Here we report a unique case of acute monoblastic leukemia with gain of i(5)(p10), tetrasomy 8, an unbalanced translocation der(19)t(17;19)(q23;p13.3) and mutated NPM1.

RESULTS

Bone marrow cells were examined by conventional karyotyping, fluorescence in situ hybridization (FISH) and mutation analysis at diagnosis and follow-up. At diagnosis we detected trisomy 8, an unbalanced translocation der(19)t(17;19)(q23;p13.3) and mutated NPM1. During the course of the disease we observed clonal evolution with gain of i(5)(p10), tetrasomy 8 and eventually duplication of der(19)t(17;19)(q23;p13.3). By using the der(19)t(17;19) as clonal marker, we found that i(5)(p10) and tetrasomy 8 were secondary genetic events and that tetrasomy 8 had clonally evolved from trisomy 8.

CONCLUSIONS

This case of acute monoblastic leukemia presents a combination of rare chromosomal abnormalities including the unbalanced translocation der(19)t(17;19)(q23;p13.3), hitherto un-reported in AML. In addition, our case supports the hypothesis of a step-wise clonal evolution from trisomy 8 to tetrasomy 8 in AML. Reporting and collecting data of rare chromosomal abnormalities will add information to AML disease, progression and prognosis, and may eventually translate to improved patient management.

Chromosomal mosaicism in cleavage-stage human embryos and the accuracy of single-cell genetic analysis

PURPOSE

Our purpose was to assess the effect of chromosomal mosaicism in cleavage-stage human embryos on the accuracy of single-cell analysis for preimplantation genetic diagnosis.

METHODS

Multicolor fluorescence in situ hybridization with X, Y, and 7 or X, Y, 7, and 18 chromosome-specific probes was used to detect aneuploidy in cleavage-stage human embryos.

RESULTS

Most nuclei were diploid for the chromosomes tested but there was extensive mosaicism including monosomic, double-monosomic, nullisomic, chaotic, and haploid nuclei.

CONCLUSIONS

Identification of sex by analysis of a single cleavage-stage nucleus is accurate but 7% of females are not identified. One or both parental chromosomes 7 were absent in at least 6.5% of the nuclei. With autosomal recessive conditions such as cystic fibrosis, carriers would be misdiagnosed as normal or affected. With autosomal dominant conditions, failure to analyze the affected parents allele (1.6-2.5%) would cause a serious misdiagnosis and analysis of at least two nuclei is necessary to reduce errors.