Clinical measurement of cellular DNA damage hypersensitivity in patients with DNA repair defects

• Background: DNA repair deficiency disorders are rare inherited diseases arising from pathogenic (disease-causing) variants in genes involved in DNA repair. There are no standardized diagnostic assays for the investigation of pathological significance of unknown variants in DNA repair genes. We hypothesized that our assays for measuring in vitro patient blood cell hypersensitivity to DNA-damaging agents can be used to establish the pathological significance of unknown variants in DNA repair genes. Six patients with variants in the DNA repair genes PRKDC (two siblings), DCLRE1C (two siblings), NBN, and MSH6 were included. Here, we used the cell division assay (CDA) and the gamma-H2AX assay, which were both developed and clinically validated by us, to measure patient cell hypersensitivity in response to ionizing radiation, mitomycin C, cytarabine and doxorubicin. Results: Radiation hypersensitivity was detected in the two patients with variants in the PRKDC gene (p < 0.0001 for both at 3.5 Gy), and the two patients with DCLRE1C variants (p < 0.0001 at 3.5 Gy for sibling 1 and p < 0.0001 at 1 Gy for sibling 2). The cells from the patients with the PRKDC variant were also deficient in removing gamma-H2AX (p < 0.001). The cells from the patient with variants in the NBN gene were hypersensitive to mitomycin C (p = 0.0008) and deficient in both induction and removal of gamma-H2AX in response to radiation. Conclusions: The combination of the CDA and the gamma-H2AX assay is useful in investigating the significance of unknown variants in some DNA repair genes.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Medicinsk genetik (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Medical Genetics (hsv//eng)

NATURVETENSKAP  -- Biologi -- Cellbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Cell Biology (hsv//eng)

Nyckelord

Cell division assay (CDA)

gamma-H2AX

DNA repair deficiency disorders

Ionizing radiation sensitivity

Mitomycin C sensitivity

Clinical

diagnosis

strand break repair

functional-role

fanconi-anemia

gamma-h2ax

diseases

assay

nbs1

Genetics & Heredity

Research & Experimental Medicine

Cell division assay (CDA)

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)