Epidemiology of Primary Immunodeficiency in Iceland.

PURPOSE: Primary immunodeficiencies (PID) are rare heterogeneous diseases. Little is known about the prevalence of PID in Iceland and no national registry exists. The aim of the study was to describe the epidemiology of PID in Iceland. METHODS: Using The European Society's for Immunodeficiencies (ESID) criteria for PID, information about individuals with a known PID between 1990 and 2010 in Iceland were collected from inpatient registries of the National University Hospital of Iceland, the Department of Immunology and from clinical immunologists. Selective IgA deficiency, mannan binding lectin deficiency and secondary immunodeficiencies were excluded RESULTS: Sixty six individuals met the study criteria, 35 of them (53%) were females. Four patients died during the study period from PID- or treatment related complications and two moved abroad. In the beginning of 2011 there were 60 individuals living in Iceland with a known PID diagnosis meeting ESID's criteria. Estimated prevalence for PID in the Icelandic population of 318.452 habitants was 18.8 for 100.000 inhabitants. Predominantly antibody disorders comprised the largest category of PID in Iceland. CONCLUSIONS: The prevalence of PID is high in Iceland compared to reports from other nations. Our patient data are easily accessible and a central laboratory measures the immune parameters. This high prevalence may indicate that PID is more common than generally recognized.

[Extremely low birthweight infants in Iceland 1991-95. Risk factors for perinatal and neonatal death]. / Litlir fyrirburar á Islandi 1991-95. Ahaettuthaettir fyrir burdarmálsog nýburadauda.

OBJECTIVE: Survival of extremely low birthweight infants with birthweight <1000 g (ELBW) has increased in recent years, parallel to decline in perinatal mortality rate. This study was part of a geographically defined national study on survival, health, development and longterm outcome of ELBW infants in Iceland 1991-95 focusing on infant and maternal health risk factors affecting infant survival. MATERIAL AND METHODS: Information was collected from the National Birth Registry on births and survival of ELBW infants weighing 500-999 g born in Iceland 1991-95. Information was obtained from hospital records of all liveborn ELBW infants and their mothers regarding maternal health, pregnancy, birth, diseases in the newborn period, lifespan and causes of death. Information on causes of death was collected from autopsy records of deceased infants. Comparison was made between the deceased ELBW infants and the control infants that survived. RESULTS: The study group consisted of 28 infants that died and a control group of 32 infants that survived. Most of the infants died in the first 24 hours after birth (47%). There was no significant difference in birthweight in the two groups nor regarding age of mothers, smoking, alcohol use and medication. Nearly all mothers of deceased infants (97%) had health problems during the pregnancy, compared to 66% mothers in the control group. Mothers of deceased infants had significantly more common infections (p=0.004). Significant difference was found regarding respiratory distress syndrome and intraventricular hemorrhage in infants that died (p=0.001). CONCLUSIONS: The results of the study support that short pregnancy, infection during pregnancy and intraventricular hemorrhage were the main risk factors causing death of ELBW infants in the perinatal and neonatal period in 1991-95.

A genetic contribution to inflammatory bowel disease in Iceland: a genealogic approach.

BACKGROUND AND AIMS: Both genetic and environmental factors play a role in the development of Crohn's disease (CD) and ulcerative colitis (UC), collectively known as inflammatory bowel disease (IBD). The aim of this study was to estimate the genetic component in IBD in Iceland. METHODS: A population-based sample, representing everyone diagnosed with IBD in Iceland from 1950 to 1996, was studied using a computerized population-wide genealogic database. The relationships among the patients were analyzed by calculating the kinship coefficient and the relative risk. RESULTS: The kinship coefficients for the patients were significantly greater than the mean kinship coefficient for the controls ( P < 10 -6 ). The risk ratio for siblings of IBD, UC, and CD patients was 5.0 ( P < 0.001), 5.9 ( P < 0.001), and 4.1 ( P = 0.033), respectively. The cross-risk ratio for siblings of UC patients developing CD (or vice versa) was 2.6 ( P = 0.015). CONCLUSIONS: The results indicate that the IBD patients are more closely related than the controls, which strongly supports the involvement of a genetic component in the development of IBD in Icelandic patients. We find that the increase in risk for relatives of UC probands to develop UC, or relatives of CD probands to develop CD, is greater than the increase in risk for relatives of UC probands to develop CD, or relatives of CD probands to develop UC.

Familial predisposition and cosegregation analysis of adult obstructive sleep apnea and the sudden infant death syndrome.

Previous studies suggest a familial link between adult obstructive sleep apnea syndrome (OSAS) and sudden infant death syndrome (SIDS). However, most of these studies were hampered by the availability of too few cases of SIDS to draw conclusions. To examine the familial nature of this association in Iceland, hospital-based lists of all patients who were diagnosed with OSAS (n = 2,350) and SIDS (n = 58) from 1979 to 1998 were used to separately determine the familial occurrence of OSAS and SIDS and to search for evidence of cosegregation of these conditions in Icelandic families, using a nationwide genealogy database. The risk ratio for a first-degree relative of a patient with OSAS was 2.0 (1.7-2.8, 95% confidence interval). The risk ratio of the more severely affected patients with OSAS was slightly higher (2.3). Likewise, the kinship coefficient (KC) for the OSAS patient group, which determines the relatedness of the patients, was significantly larger than the mean KC of 1,000 matched control groups. Estimation of the KC for the SIDS group showed a trend toward significance when compared with control groups, but after excluding one of the half-siblings in the SIDS group from the analysis, the difference did not show any trend toward significance. Although the results of the analysis of the relatedness between all patients with OSAS and infants who died of SIDS were not significant, a trend toward significance was evident when the data were separately analyzed for the more severely affected patients with OSAS. Collectively, these results demonstrate a strong familial component in OSAS and suggest that infants who died of SIDS may have shared some of the same susceptibility factors with OSAS.