Haematological malignancies in childhood in Croatia: investigating the theories of depleted uranium, chemical plant damage and 'population mixing'.

Some of potential causes proposed to explain the reported increase of haematological malignancies in childhood during or after the war period in several countries include depleted uranium, chemical pollution and population mixing theory. The aim of this study was to define the population of Croatian children aged 0-14 years who were potentially exposed to each of those risks during the war and to investigate any possible association between the exposure and the incidence of haematological malignancies. The authors analyzed the data reported by the Cancer Registry of Croatia during the pre-war period (1986-1990), war period (1991-1995) and post-war period (1996-1999). In the group of 10 counties potentially exposed to depleted uranium and two counties where chemical war damage occurred, no significant difference in incidence of the studied haematological malignancies was noted in comparison to pre-war period. The incidence of lymphatic leukaemia significantly increased in four counties where population mixing had occurred during the war period, supporting the 'mixing theory'. In those counties, the incidence of Hodgkin's lymphoma decreased during and after the war. In Croatia as a whole, decreases in incidence of myeloid leukaemias during war and non-Hodgkin lymphoma after the war were noted.

Inbreeding and nephrolithiasis in Croatian island isolates.

The aim of this study was to investigate a recessive genetic component in susceptibility to nephrolithiasis (NL) by comparing its prevalence in highly inbred, moderately inbred and non-inbred villages of three Croatian islands: Brac, Hvar and Korcula. The average inbreeding coefficient of each village population (F) was estimated in a random sample of 20-30% adults from 14 villages using Wright's path method (based on genealogical information), isonymy data and average deviation from Hardy-Weinberg expectations for MN, Ss and Kk serogenetic polymorphisms. The six villages with the greatest genealogical F value (0.025-0.049; current total population N=1,401), the four with intermediate value (0.012-0.015; N=998) and the four with the smallest value (0.002-0.008; N=1,500) were chosen for this study. Medical records of entire populations were reviewed and the diagnosis of NL was established according to unified criteria, based on the information from the specialists in general hospitals and on the agreement in diagnosis between the investigators and local general practitioners. The variance in environmental and socio-cultural factors between villages was shown to be minimal. Prevalence of NL in each village was standardised by sex and age to the total population of all 14 villages. The standardized prevalence of NL was 1.5% in the group of villages with low F, 2.3% in the group with moderate F (p<0.10), and 5.4% in the group with high F (p<0.001). The correlation factor between F values by villages and the standardized prevalence of NL was 0.45 (p<0.05). The study showed that a large number of predominantly recessive genetic factors might mediate the susceptibility to formation of renal stones in humans.

Inbreeding and learning disability in Croatian island isolates.

The aim of this study was to investigate the prevalence of learning disability (LD) in isolate populations with different inbreeding coefficients (F). Prevalence of LD and F were determined in 10 villages from five Croatian islands: Brac, Hvar, Korcula, Lastovo and Susak. For the purpose of this study, LD was defined as the inability to attend the public school system. As the elementary schools (grade 1-8) in the place of the study are both public and compulsory, the assessment of child's inability to attend the school is performed at the age of six. This is required by all children in the country based on standard set of tests of cognitive performance defined by the Ministry of Education and Culture of the Republic of Croatia. The average inbreeding coefficients in each village population (F) were estimated in a random sample of 20-30% adults in each of the 10 villages based on 4 ancestral generations and using Wright's path method. Prevalence of LD ranged from 0.43% to 2.47%, and the inbreeding coefficients ranged from 0.8% to 4.9%. The Pearson's correlation coefficient between F and LD prevalence was 0.80 (p < 0.01). Although the relative risk per 5% inbreeding appeared very high (about 10), the absolute risk only increased from 0.18% to 1.77%. The genetic effect of inbreeding (GEI) was approximately 0.69% and the population-attributable fraction 76.6%. A review of the literature and the results of this study lead to a conclusion that a very large number of predominantly recessive genetic factors might mediate the genetic susceptibility to various forms of LD in these populations.