Fanconi's anaemia: report of a patient with significant chromosomal abnormalities in bone marrow cells

Cancer in Fanconi anemia, 1927-2001

BACKGROUND

Fanconi anemia (FA) is an autosomal recessive disease associated with an abnormal response to DNA damage. Although FA is well known for the association of aplastic anemia and characteristic birth defects, leukemia and solid tumors also occur at a high rate in this group of patients. A review of all reported cases is informative with regard to the specific types of cancer, the ages at which they occur, and the cumulative probability of their development.

METHODS

Medline and bibliographies of publications were searched for articles containing "Fanconi's anemia" or "aplastic anemia" and all cases of FA from 1927 through 2001 were included in the database. Cancer cases were identified within these reports. Descriptive statistical analyses were performed using Stata7 software.

RESULTS

One thousand three hundred cases of FA were identified. Nine percent had leukemia (primarily acute myeloid leukemia), 7% had myelodysplastic syndrome, 5% had solid tumors, and 3% had liver tumors. Patients with cancer were older than the cancer-free patients at the time of diagnosis of FA. The median age for cancer (including leukemia) was 16, compared with 68 in the general population. The most frequent solid tumors were aerodigestive and gynecological carcinomas. In approximately 25% of patients with cancer, the malignancy preceded the diagnosis of FA.

CONCLUSIONS

If the competing risks of aplastic anemia and leukemia could be removed, the estimated cumulative probability of development of a solid tumor in FA patients is 76% by the age of 45 years. Carcinogenic pathways and cancer prevention, surveillance, and treatment can be studied to advantage in this genetic model of human cancer.

Genetic diseases in Lebanon

Lebanon has a high incidence of common and rare genetic diseases, due probably to the mosaic different ethnic origins and the high rate of consanguineous marriages in certain communities. Two major investigations, exploring the genetic structure of the Lebanese population, indicated the population to be caucasiods (though Oriental traits were found). These investigations involved studies of dermatoglyphics, and type and distribution of genetic markers and protein variants. Recorded genetic diseases, some characteristic of ethnic group or particular to a geographic region include familial paroxysmal polyserositis, familial hypercholesterolemia, hypothroidism, the Dyggve-Melchoir-Clausen syndrome, Sandhoff disease, and various genetic hematologic diseases. Genetic counseling and care to patients with genetic diseases is available in Beirut from the Faculty of Medicine at American University and St. Joseph University. Also, the Lebanese National Council for Scientific Research initiates and finances medical genetics programs.

Clinical and cytogenetic observations during a six-year period in an adult with Fanconi's anaemia

A male adult patient suffering from Fanconi's anemia is described who was diagnosed 5 years before the onset of clinical symptoms by cytogenetic findings of chromosomeinstability in a lymphocyte culture. Repeated clinical, haematological and biochemical investigations of the untreated patient have been made during the observation period of six years. In the same period of time cytogenetic studies have been carried out which show no correlation in results compared with the clinical or physical findings. Four well defined lymphocyte clones have been discovered. The patient is still under observation of the clinic and the cytogenetic department.

Induction by alkylating agents of sister chromatid exchanges and chromatid breaks in Fanconi's anemia

Sister chromatid exchanges, which may reflect chromosome repair in response to certain types of DNA damage, provide a means of investigating the increased chromosome fragility characteristic of Fanconi's anemia. By a recently developed technique using 33258 Hoechst and 5-bromodeoxyuridine, it was observed that the baseline frequency of sister chromatid exchanges in phytohemagglutinin-stimulated lymphocytes from four males with Fanconi's anemia differed little from that of normal lymphocytes. However, addition of the bifunctional alkylating agent mitomycin C (0.01 or 0.03 mug/ml) to the Fanconi's anemia cells during culture induces less than half of the increase in exchanges found in identically treated normal lymphocytes. This reduced increment in exchanges in accompanied by a partial suppression of mitosis and a marked increase in chromatid breaks and rearrangements. Many of these events occur at sites of incomplete chromatid interchange. The increase in sister chromatid exchanges induced in Fanconi's anemia lymphocytes by the monofunctional alkylating agent ethylmethane sulfonate (0.25 mg/ml) was slightly less than that in normal cells. Lymphocytes from two sets of parents of the patients with Fanconi's anemia exhibited a normal response to alkylating agents, while dermal fibroblasts from two different patients with Fanconi's anemia reacted to mitomycin C with an increase in chromatid breaks, but a nearly normal increment of sister chromatid exchanges. The results suggest that chromosomal breaks and rearrangements in Fanconi's anemia lymphocytes may result from a defect in a form of repair of DNA damage.