Incidence of insulin-dependent diabetes mellitus among Sardinian-heritage children born in Lazio region, Italy.
BACKGROUND
The relative importance of genetic and environmental factors in causing insulin-dependent diabetes mellitus (IDDM) is unknown. We studied this question by assessing the incidence of the disease in children, born in a region with a low incidence of IDDM (Lazio), but whose parents came from a region with high incidence (Sardinia).


METHODS
We identified all IDDM cases that occurred between 1989 and 1994. We used as the denominator the number of children aged 0-14 born in Lazio of Sardinian parents to calculate incidence. We compared this rate with the incidences of IDDM in the populations of Lazio and Sardinia.


RESULTS
The age-adjusted incidence of IDDM in Sardinian-heritage children born and living in Lazio was 33.8 per 100,000 per year (95% CI 7.0-99.0) for those with two Sardinian parents, and 15.9 (8.7-26.6) for those with only one parent from Sardinia. The former incidence was not different from that recorded in Sardinia (34.4, 31.3-37.9), but was fourtold that of Lazio-heritage children (7.9, 7.1-8.8).


CONCLUSIONS
Our results show that two different ethnic groups living in the same region have a fourfold difference in incidence of IDDM. Children of Sardinian-heritage born in Lazio have the same incidence as the population of origin, which is genetically prone to the disease. Moreover, children with one Sardinian parent had a rate half that of Sardinians and double that of the indigenous population. We conclude that in a given population genetic susceptibility determines the frequency of IDDM in response to the environmental challenge.
Muntoni
S
S
Centro per le Malattie Dismetaboliche e l'Arterlosclerosi, Associazione ME.DI.CO, Cagilari, Italy.
Fonte
M T
MT
Stoduto
S
S
Marietti
G
G
Bizzarri
C
C
Crinò
A
A
Ciampalini
P
P
Multari
G
G
Suppa
M A
MA
Matteoli
M C
MC
Lucentini
L
L
Sebastiani
L M
LM
Visalli
N
N
Pozzilli
P
P
Boscherini
B
B
Muntoni
S
S
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000208:ethnology* / Q000209:etiology / Q000235:genetics*; D004777:Environment; D005260:Female; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology / Q000208:ethnology; D008297:Male; D010290:Parents