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ataxia-telangiectasia-like disorder (ATLD)

The AT-like disorder is caused by the mutation in the MRE11A gene. Patients' cells exhibit chromosomal instability, increased sensitivity to ionizing radiation, defective induction of stress-activated signal transduction pathways and radioresistant DNA synthesis. It was linked with ataxia and ocular apraxia, with the absence of tumor developement or telangiectasia. The clinical features are very similar to AT's but with milder clinical course, and therefore it is hard to distinguish both diseases. Moreover, the molecular analysis needs to be very precise, as the ATM gene maps to the locus 11q23 and MRE11A gene maps to 11q21. Stewart et al. (1999) suggested that about 6% of AT cases might have the MRE11A mutations.
Gene map locus 11q21.

Interestingly, the proteins expressed by the hMre11 (defective in ATLD) and Nbs1 (defective in NBS) genes exist in the cell as a complex, along with a third protein expressed by the hRad50 gene. This complex, known as the MRN complex, plays an important role in DNA damage repair and signaling and is required to recruit ATM to the sites of DNA double strand breaks. Mre11 and Nbs1 are also targets for phosphorylation by the ATM kinase. Thus, the similarity of the three diseases can be explained in part by the fact that the protein products of the three genes mutated in these disorders interact in common pathways in the cell.

ABREVIATION(S):
ATLD

TYPE: sensitivity to radiation, NO CANCER development, chromosomal instability

Related patway(s): homologous recombination (HR), non-homologous end-joining (NHEJ)

DNAtraffic protein(s) related to disease: MRE11A

OMIM: 604391

Last modification date: Aug. 17, 2011