Studies on herediatary spherocytosis in Iceland

A novel ENU-induced ankyrin-1 mutation impairs parasite invasion and increases erythrocyte clearance during malaria infection in mice

Genetic defects in various red blood cell (RBC) cytoskeletal proteins have been long associated with changes in susceptibility towards malaria infection. In particular, while ankyrin (Ank-1) mutations account for approximately 50% of hereditary spherocytosis (HS) cases, an association with malaria is not well-established, and conflicting evidence has been reported. We describe a novel N-ethyl-N-nitrosourea (ENU)-induced ankyrin mutation MRI61689 that gives rise to two different ankyrin transcripts: one with an introduced splice acceptor site resulting a frameshift, the other with a skipped exon. Ank-1^(MRI61689/+) mice exhibit an HS-like phenotype including reduction in mean corpuscular volume (MCV), increased osmotic fragility and reduced RBC deformability. They were also found to be resistant to rodent malaria Plasmodium chabaudi infection. Parasites in Ank-1^(MRI61689/+) erythrocytes grew normally, but red cells showed resistance to merozoite invasion. Uninfected Ank-1^(MRI61689/+) erythrocytes were also more likely to be cleared from circulation during infection; the “bystander effect”. This increased clearance is a novel resistance mechanism which was not observed in previous ankyrin mouse models. We propose that this bystander effect is due to reduced deformability of Ank-1^(MRI61689/+) erythrocytes. This paper highlights the complex roles ankyrin plays in mediating malaria resistance.

A systematic review of hereditary spherocytosis reported in Chinese biomedical journals from 1978 to 2013 and estimation of the prevalence of the disease using a disease model

Epidemiological information of hereditary spherocytosis in China is slight. This systematic review summarizes the number of cases of hereditary spherocytosis reported in China Biology Medicine disc from 1978 to 2013. In total, 2,043 cases were reported in the past 36 years. We describe its distribution from time and space. We also estimate the literature reported prevalence of hereditary spherocytosis by DisMod-II software, overall prevalence in China was estimated to be: 1.27 cases per 100,000 people in males and 1.49 cases per 100,000 people in females. All results suggest a stronger network of diagnosis and treatment including all levels of hospitals should be created to improve healthcare for hereditary spherocytosis and even other rare diseases in the future, meanwhile we can obtain more useful information for orphan drug designation purposes and make public health decisions regarding such diseases through the use of the burden of disease models.

Hereditary Spherocytosis in a Middle-aged Man Complicated with Common Bile Duct Stones

Hereditary spherocytosis is the most common form of hemolytic anemia and is characterized by spherical, osmotically fragile erythrocytes that are selectively trapped by the spleen. Hereditary spherocytosis is typically diagnosed in childhood. We herein experienced a rare case of hereditary spherocytosis diagnosed in middle age. The patient presented with cholelithiasis and hyperbilirubinemia. He had no anemia and was asymptomatic with mild splenomegaly. In the differential diagnosis of these symptoms, the possibility of hereditary spherocytosis should be considered, even in patients who are middle-aged and lack anemia.

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.

Hereditary spherocytosis

Hereditary spherocytosis is a common inherited disorder that is characterised by anaemia, jaundice, and splenomegaly. It is reported worldwide and is the most common inherited anaemia in individuals of northern European ancestry. Clinical severity is variable with most patients having a well-compensated haemolytic anaemia. Some individuals are asymptomatic, whereas others have severe haemolytic anaemia requiring erythrocyte transfusion. The primary lesion in hereditary spherocytosis is loss of membrane surface area, leading to reduced deformability due to defects in the membrane proteins ankyrin, band 3, beta spectrin, alpha spectrin, or protein 4.2. Many isolated mutations have been identified in the genes encoding these membrane proteins; common hereditary spherocytosis-associated mutations have not been identified. Abnormal spherocytes are trapped and destroyed in the spleen and this is the main cause of haemolysis in this disorder. Common complications are cholelithiasis, haemolytic episodes, and aplastic crises. Splenectomy is curative but should be undertaken only after careful assessment of the risks and benefits.

Guidelines for the diagnosis and management of hereditary spherocytosis

Hereditary spherocytosis (HS) is a heterogeneous group of disorders with regard to clinical severity, protein defects and mode of inheritance. It is relatively common in Caucasian populations; most affected individuals have mild or only moderate haemolysis. There is usually a family history, and a typical clinical and laboratory picture so that the diagnosis is often easily made without additional laboratory tests. Atypical cases may require measurement of erythrocyte membrane proteins to clarify the nature of the membrane disorder and in the absence of a family history, occasionally molecular genetic analysis will help to determine whether inheritance is recessive or non-dominant. It is particularly important to rule out stomatocytosis where splenectomy is contraindicated because of the thrombotic risk. Mild HS can be managed without folate supplements and does not require splenectomy. Moderately and severely affected individuals are likely to benefit from splenectomy, which should be performed after the age of 6 years and with appropriate counselling about the infection risk. In all cases careful dialogue between doctor, patient and the family is essential. Laparoscopic surgery, when performed by experienced surgeons, can result in a shorter hospital stay and less pain.

Hereditary spherocytosis—defects in proteins that connect the membrane skeleton to the lipid bilayer

The molecular causes of hereditary spherocytosis (HS) have been unraveled in the past decade. No frequent defect is found, and nearly every family has a unique mutation. In dominant HS, nonsense and frameshift mutations of ankyrin, band 3, and beta-spectrin predominate. Recessive HS is most often due to compound heterozygosity of defects in ankyrin, alpha-spectrin, or protein 4.2. Common combinations include a defect in the promoter or 5'-untranslated region of ankyrin paired with a missense mutation, a low expression allele of alpha-spectrin plus a missense mutation, and various mutations in the gene for protein 4.2. In most patients' red cells, no abnormal protein is present. Only rare missense mutations, like ankyrin Walsrode (V463I) or beta-spectrin Kissimmee (W202R), have given any insight into the functional domains of the respective proteins. Although the eminent role of the spleen in the premature hemolysis of red cells in HS is unquestioned, the molecular events that cause splenic conditioning of spherocytes are unclear. Electron micrographs show that small membrane vesicles are shed during the formation of spherocytes. Animal models give further insight into the pathogenetic consequences of membrane protein defects as well as the causes of the variability of disease severity.

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.

Comparison of acidified glycerol lysis test, Pink test and osmotic fragility test in hereditary spherocytosis: effect of incubation

In this study we compared the results of the acidified glycerol lysis test, the Pink test and the osmotic fragility test in 38 patients with hereditary spherocytosis and in healthy controls. The sensitivity of the acidified glycerol lysis test was 81.6% when performed within 3 h after blood collection. After incubating for 24 h, the sensitivity increased to 100% whereas the specificity remained maximal. Similar incubation did not improve the diagnostic utility of the Pink test. All patients, but none of the controls, showed a positive osmotic fragility test. It is concluded, because of sensitivity and specificity in this study, that the acidified glycerol lysis test after incubation and the osmotic fragility test are superior to the Pink test in detecting spherocytosis.

Does preincubation of the red blood cells contribute to the capability of the osmotic fragility test to detect very mild forms of hereditary spherocytosis?

During incubation for 24 h at 37 degrees C, erythrocytes from patients with hereditary spherocytosis (HS) undergo a greater increase in osmotic fragility than do normal cells, and this procedure has been recommended for differentiating more clearly between patients with very mild HS and normal subjects. The greater effect of preincubation on erythrocytes from patients with HS was confirmed, but, except in cases demonstrating a markedly increased osmotic fragility before incubation, this effect was outweighed by a simultaneous loss of test precision. It therefore seems that preincubation does not significantly contribute to the capability of the osmotic fragility test to detect very mild forms of HS.

High prevalence of increased osmotic fragility of red blood cells among Norwegian blood donors

Increased osmotic fragility of red blood cells was found in 9 out of 1008 Norwegian blood donors. In addition, increased osmotic fragility was found in 3 out of 23 first grade relatives and in 1 out of 4 spouses of individuals with the same condition. Finally, there was a positive correlation between increased osmotic fragility and morphological signs of spherocytosis (P less than 0.05). No definite conclusions with respect to underlying mechanism(s) for this high prevalence of non-symptomatic increased osmotic fragility can be offered, but very mild hereditary spherocytosis, environmental factors and even a normal variant, never associated with haemolysis, may have contributed. Furthermore, until more specific and sensitive laboratory techniques have been introduced, a proper distinction between these 3 conditions cannot be made.

The normal range of osmotic fragility of red blood cells

With the technique of Parpart et al (1947), the normal range for osmotic fragility of red blood cells had been estimated to include 5%--45% haemolysis at a salt concentration corresponding to 4.5 g NaCl/l (Dacie 1954). This estimate may be questioned, however. Thus, nearly 20% of the data obtained from 50 presumably healthy subjects fell outside these limits. Furthermore, the distribution pattern was very asymmetric with erroneously small standard deviation. On the other had, if the technical conditions (salt concentration, buffer) were properly adjusted, nearly all the observations were located with the straight part of the s-shaped haemolysis curve and scattered symmetrically around the mean. Under these conditions, the normal range (mean +/- 2 SD) included 22%--88% haemolysis. Moreover, this wider range included about 95% of the observations, even adapted to the original experimental situation. The present estimates should therefore replace earlier statements in the literature.

Haemolysis in athletes due to hereditary spherocytosis

Three athletes, one cross-country skier and two middle distance runners, experiencing poor response to intensified training and decline in performance during prolonged periods of frequent competitions, associated with a tendency to develop anaemia, were found to have spherocytosis, and increased osmotic fragility of the red blood cells. All had family members with the same blood abnormality, but without symptoms. The observations suggest that the frequency of hereditary spherocytosis is higher than indicated by overtly affected cases and that mild cases are easily overlooked. Hereditary spherocytosis should be looked for in athletes with a tendency to decline in blood haemoglobin concentration during periods of intensive training and competition.