Familial leukemia: description of two kindreds and a review of the genetic aspects of the disease

Consanguinity and childhood acute lymphoblastic leukaemia: a case-control study

Background

Consanguineous marriage is widely practised across the world. Its effect on acute lymphoblastic leukaemia (ALL) is controversial as both parents share some of the genes which might increase the incidence of sharing recessive genes. However, other theories suggest that consanguinity might have a protective factor as it does for other types of cancers. This study aims to study childhood ALL and consanguinity.

Methods

This is a case-control study, conducted in the major paediatric hospital in Damascus, Syria, using medical records. Case group included children with ALL, while control group included other patients and were matched by gender and age.

Results

This study comprised 386 patients, 193 of which were cases. Overall, 136 were of consanguineous marriages (36.8%), and there was no difference in consanguinity overall between cases and controls. However, when only comparing non-consanguineous parents and fourth-degree consanguinity, fourth degree was significantly higher among case group, suggesting a negative correlation OR = 0.387 (0.187–0.801) in contrast to third-degree consanguinity which was no significantly different when comparing the two groups (p > 0.05). We found no significant association between ALL and having a family history of cancer (p > 0.05) or between parents’ educational level and case-control groups (p > 0.05).

Conclusion

Our research suggests a negative association between fourth-degree consanguinity and childhood leukaemia. This was not observed with a third-degree consanguinity. Previous studies had contradicting data on consanguinity and ALL which demonstrates the need for further research.

Consanguinity and family history of cancer in children with leukemia and lymphomas

BACKGROUND

In native population of the United Arab Emirates (UAE), the rate of consanguineous marriages is 50.5%. This study was designed to determine whether the rates of consanguinity and family history of cancer among the families of children with lymphoid malignancy are different from those in the general population.

METHODS

The study comprised 117 patients from the whole of the country with acute lymphocytic leukemia (ALL) and Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL), ranging in age from 2 to 14 years. The consanguinity rate in the study group was compared with the rate in the general population. To study family history of cancer, the authors matched patients with 117 controls. In a telephone interview, each mother was asked to provide data regarding the biologic relationship between her and her husband as well as that between both sets of grandparents; each was also asked whether any family relative had a cancer and, if so, of what type.

RESULTS

Among the 69 ALL cases, 80% of families were consanguineous and 20% were nonconsanguineous. Among the 26 NHL and 22 HL cases, each group included 3 consanguineous families, 12% and 14%, respectively. The consanguinity rates for ALL, NHL, and HL were all significantly different from the 50.5% consanguinity rate in the UAE population (all three P values < 0.0001). The family history of cancer was more often positive in ALL patients than in controls (odds ratio, 2.14; confidence interval, 1.01--4.53). Overall and for each lymphoid malignancy, there was no difference in family history of cancer between consanguineous and nonconsanguineous groups of cases.

CONCLUSIONS

The consanguinity rate in the families of patients with ALL is significantly higher and in those with NHL and HL significantly lower than that in the UAE population. The family history of cancer is more often positive among ALL cases than controls--consanguinity having no effect.

Familial aggregation of colorectal cancer in Egypt

We have investigated the familial aggregation of colorectal cancer and hereditary nonpolyposis colorectal cancer (HNPCC) in Egypt because of the high incidence of colorectal cancer in Egyptian children and young adults and the prevalence of consanguinity there. In a pilot study, we conducted detailed interviews with 111 Egyptian colorectal cancer patients and 111 healthy Egyptian controls about their family histories of colorectal cancer, and other cancers, consanguinity, age at diagnosis, symptoms and recurrence. Eight patients (7.2%) had one or more first- or second-degree relatives under age 40 with colorectal cancer, suggestive of HNPCC by the Amsterdam criteria. One of these families had a typical history of HNPCC, with 4 relatives having colorectal cancer in 3 generations; 3 of these relatives were younger than age 45 at colon cancer diagnosis, and other relatives had extracolonic tumors. Another 14 patients (12.6%) had a first- or second-degree relative with a family history of other neoplasms such as endometrial, urinary and hepatobiliary cancers that could also be related to HNPCC. Four patients with early-onset colon cancer and a family history of other HNPCC-related cancers reported that their parents were first-degree cousins.

Pediatric cancer: environmental and genetic aspects

One in 600 children 0-16 years of age develop cancer, and 60% to 70% of them are cured. Projection of the data indicates that by the turn of the century, 1 of every 900 individuals between the ages of 16 and 44 years will be a cancer survivor. In the adult population, carcinogens and irradiation play a major role in oncogenesis. In the pediatric population other factors are probably dominant. Children of low socioeconomic groups, with nutritional deficiencies, are more exposed to viral infections at a very early age and have a greater chance of developing tumors such as Burkitt lymphoma or mixed cellularity Hodgkin disease. Other factors such as hormone-assisted conception or in vitro fertilization may have carcinogenic potential, although this has yet to be determined. Maternal diet during pregnancy, especially low folic acid consumption periconception, may have bearing on the fetus's risk of developing malignancy. The hazards of exposure to electric and magnetic fields from high-voltage transmission lines, home electric appliances, video display terminals, or residence near nuclear plants, although very doubtful, are included in the list of cancer promoters in children. Activated oncogenes, mutated suppressor genes, mismatch repair genes, nucleotide excision genes, and loss of imprinting genes are beginning to evolve as important factors in carcinogenesis. The more in-depth information on genetic and environmental factors should provide new data on the evolution of pediatric tumors and possibly on their prevention.