Hereditary elliptocytosis in Iceland

Multigenerational information: the example of the Icelandic Genealogy Database

The first part of the chapter describes the Icelandic Genealogical Database, how it was created, what it contains, and how it operates. In the second part, an overview of research accomplished with material from the database is given.

Studies on herediatary spherocytosis in Iceland

Thirty members with typical hereditary spherocytosis (HS) and over 90 apparently unaffected members belonging to 12 families have been studied. Splenectomy has been performed on 22 HS patients. Of nine HS individuals, who had not undergone surgical treatment in 1957, four suffered from temporary severe anaemia, presumably due to aplastic crisis associated with influenza. One of them died, a male 18 years of age. Pedigree studies on one of the families indicate that the HS gene or genes have been transmitted through six generations over the past 200 years. Marked deficiency in the number of affected compared with the apparently unaffected members in the HS families is present. The most striking example of uneven genetic ratio is a sibship of 15 members investigated haematologically, with one suffering from typical HS. Much reduced penetration of the HS gene or the presence of the socalled "mild form" is upheld as the main explanation for the unevenness in the genetic ratio. However, families are also present in which abortions and death at an early age indicated that selection against the affected could also disturb the genetic ratio in HS families.

Hereditary elliptocytosis: spectrin and protein 4.1R

Hereditary elliptocytosis (HE) is a common disorder of erythrocyte shape, occurring especially in individuals of African and Mediterranean ancestry, presumably because elliptocytes confer some resistance to malaria. The principle lesion in HE is mechanical weakness or fragility of the erythrocyte membrane skeleton due to defects in alpha-spectrin, beta-spectrin, or protein 4.1. Numerous mutations have been described in the genes encoding these proteins, including point mutations, gene deletions and insertions, and mRNA processing defects. Several mutations have been identified in a number of individuals on the same genetic background, suggesting a "founder effect." The majority of HE patients are asymptomatic, but some may experience hemolytic anemia, splenomegaly, and intermittent jaundice.

The saga of cystatin C gene mutation causing amyloid angiopathy and brain hemorrhage--clinical genetics in Iceland

Firstly, we review investigations of hereditary cystatin C amyloid angiopathy, which is caused by a mutation in the cystatin C gene. Symptoms of brain haemorrhages, which lead to death in young adults, are the hallmark of this disorder. The mutation can now be detected by the RFLP method using Alu I restriction enzyme and cystatin C cDNA probe. Secondly, we give an overview of other clinical genetic studies in Iceland with emphasis on activities initiated or sponsored by the Genetical Committee of the University of Iceland. The list of references covers most publications on genetic studies of Icelanders.

Rheumatic diseases in an Icelandic family. Clinical and immunological survey

We have studied 192 members of a highly inbred Icelandic family with clustering of rheumatic diseases. Twelve consanguineous marriages are known in the family and 54 of 65 surviving offsprings of these (inbred group) were traced. Thirty-nine family members were affected by rheumatic diseases; 18 of them belonged to the inbred group. Eleven of 20 family members with rheumatoid arthritis (RA) came from the same inbred group. Eleven of the inbred group had a positive Rose-Waaler test for rheumatoid factor (RF) and the inbred group had significantly higher serum levels of IgG and IgM than an age and sex matched group from the family. Serum IgM RF was significantly associated with the age of the family members, but IgA RF and IgG RF did not show any such association. The possible role of recessive genes in the rheumatic diseases, as well as the inbreeding effect regarding certain extended HLA-complotypes is discussed.

Hereditary elliptocytosis: morphologic abnormalities during acute hepatitis

A 10-year-old black girl with hereditary elliptocytosis had a transient increase in hemolysis and unusual red cell morphologic changes during an episode of acute hepatitis. Changes in membrane lipids of these elliptocytes with defective membrane skeletal protein and abnormal distribution of cholesterol may be responsible for this phenomenon.

Inherited disorders of the red cell membrane skeleton

Current knowledge of red cell membrane structure and function are briefly presented, and the pathophysiology, diagnosis, and treatment of hereditary spherocytosis, hereditary elliptocytosis, and hereditary pyropoikilocytosis are discussed.

Hereditary haemolytic ovalocytosis with defective erythropoiesis

Patients belonging to four families with 'atypical elliptocytosis' have been investigated. Clinical, haematological, erythrokinetic and enzymatic characteristics as well as the effect of splenectomy are discussed. These studies appear to define the fundamental features of a particular disorder or a variety of hereditary elliptocytosis; characterized by a genetic autosomal dominant character, moderate degree of RBC eccentricity, erythroid dysplasia with relative marrow failure and incomplete response to splenectomy.

Red cell survival studies in hereditary spherocytosis

The in vivo survival of hereditary spherocytes has been investigated with the (51)Cr red cell survival technique. Spherocytes invariably showed a shorter survival in a normal recipient than in the donor's own circulation. Moreover transfusion of spherocytes from a mother to her son, both with hereditary spherocytosis, showed that "foreign" spherocytes have a shorter survival than the "self" spherocytes of the recipient. These findings are attributed to splenic reticuloendothelial blockade, specific towards hereditary spherocytes in the patient's own circulation. There was no correlation between the Na(+) influx and the hemolytic tendency of hereditary spherocytes when the latter was measured by the survival t(1/2) in compatible normal recipients. However osmotic fragility influenced cell survival since cells with high fragility were rapidly sequestered in the normal spleen. It is suggested that both cell shape and a selective reticuloendothelial blockade in the spleen are important factors in determining the severity of hemolysis in the individual patient.