Chromosomal Instability Syndromes in Man

Linkage studies exclude the AT-V gene(s) from the translocation breakpoints in an AT-V patient

An 8-year-old girl with severe microcephaly of prenatal onset, borderline intelligence, defects of skin pigmentation, deficiency of both humoral and cellular immunity, a normal serum alpha-fetoprotein level and hypersensitivity to ionizing irradiation is described. Spontaneous chromosomal breakage in lymphocytes together with the clinical presentation led to the diagnosis of ataxia telangiectasia variant (AT-V). In addition, the patient carried a constitutional translocation of paternal origin: 46,XX,t(3;7)(q12;q31.3) pat. In subsequent linkage and haplotype studies in 12 AT-V families with microsatellite markers from each of the translocation breakpoint regions, we could clearly exclude the localization of an AT-V gene to these regions.

X-ray-sensitivity of lymphocytes of aplastic- and Diamond-Blackfan-anemia patients as detected by conventional cytogenetic and chromosome painting techniques

Frequencies of spontaneously occurring and X-ray induced, stable and unstable types of chromosome aberrations in peripheral blood lymphocytes from two groups of radiosensitive patients, i.e., aplastic anemia (AA) and Diamond-Blackfan anemia (DBA), were determined. Two types of staining methods, i.e., chromosome painting with two cocktails of chromosome-specific DNA libraries (Nos. 1, 3, X and Nos. 2, 4 and 8), as well as conventional Giemsa staining, were employed. Chromosome painting was done with single and multicolor fluorescence in situ hybridization (FISH). The frequencies of spontaneously occurring chromosome aberrations in AA and DBA patients were not significantly different from healthy individuals. Hypersensitivity to X-rays was seen both in G0 as well as in G2 phase of the cell cycle in lymphocytes from AA and DBA patients, confirming our earlier findings using micronucleus (DBA) and G2 radiosensitivity (AA) assays.

Fanconi anemia complementation group E: clinical and cytogenetic data of the first patient

The clinical and cytogenetic data of the first patient proven to belong to the fifth Fanconi anemia complementation group are described. The Turkish boy presented with psychomotoric retardation, growth retardation, retarded bone age, brachycephaly, hypotelorism, epicanthus, syndactyly, brachydactyly, renal dystopia, and cryptorchism. In addition, an asymmetrical skeletal anomaly was seen with a double distal phalanx of the left thumb and hypoplasia of the right thumb. Typical hematological features of the disorder developed, at the age of 2.5 years, about 1 year after diagnosis. Cytogenetic studies confirmed the clinical diagnosis and revealed a spontaneous chromosomal instability and hypersensitivity to the cross-linking agents diepoxybutane and Trenimon. The findings in the patient, who is considered to be the standard for the fifth Fanconi anemia complementation group, are compared with data reported for other patients affected with Fanconi anemia.

Low-grade non-Hodgkin's lymphoma after high-grade non-Hodgkin's lymphoma in a child with ataxia telangiectasia

BACKGROUND

Non-Hodgkin lymphomas (NHL) account for approximately 50% of neoplasms in patients with ataxia telangiectasia (AT). Prognosis is poor. Published data regarding the treatment of NHL in patients with AT suggested that these children respond poorly to therapy. The authors report on an infant with AT with mediastinal high-grade T-NHL who remained in continuous complete remission after chemotherapy. Diagnosis of AT was established after tumor diagnosis.

METHODS AND RESULTS

The 7-month-old boy was treated according to the acute lymphoblastic leukemia-Berlin, Frankfurt, Münster 86 protocol. The therapeutic response was prompt, but therapy had to be stopped because of severe side effects. Surprisingly, the boy remained in a stable complete remission for 3 1/2 years. Then tumors in both kidneys occurred and the child died a few months later. Postmortem examination demonstrated large tumors in both kidneys caused by a low-grade malignant lymphoma of B-cell lineage.

CONCLUSION

Congenital immune deficiency should be ruled out at diagnosis of rare malignancies in respect to age. NHL in patients with AT can be cured, but poor tolerance to chemotherapy has to be considered. Patients whose disease has been cured may be at high risk for development of a second independent malignancy.

Chromosomal breakage, endomitosis, endoreduplication, and hypersensitivity toward radiomimetric and alkylating agents: a possible new autosomal recessive mutation in a girl with craniosynostosis and microcephaly

A high frequency of spontaneous chromosomal breakage, endomitosis, endoreduplication and hypersensitivity toward both the alkylating agent Trenimon and the radiomimetric drug bleomycin was observed in phytohemagglutinin-stimulated peripheral lymphocytes from a girl with craniosynostosis, microcephaly, ptosis, bird-like facies, and moderate mental retardation. We also observed abnormal chromosomal spiralization and some aspects of abnormal cellular division. Several fruitless attempts were made to establish a cell line. The parents were consanguineous, supporting the existence of a new, rare, autosomal, recessive condition in man. The mutation might involve a gene involved in DNA repair and/or regulation of the mitotic cycle.