PROLONGED SURVIVAL OF A PATIENT WITH SICKLE CELL ANEMIA

Mitral valve prolapse in sickle cell disease: manifestation of a generalized connective tissue disorder

Previous studies have shown an association of sickle cell disease with generalized connective tissue disorders such as pseudoxanthoma elasticum. We recently documented an unexpectedly high prevalence of mitral valve prolapse, a connective tissue disorder, in sickle cell disease. To investigate this association, skin biopsies were analyzed from 32 sickle cell disease patients, 11 of whom had mitral prolapse. Total and type III collagen, collagen solubility, and uronic acid were not different between the patients with or without mitral prolapse (p greater than 0.05). Computerized morphometric quantitation of the volume fraction of elastic fibers was greater in sickle cell disease patients than in 10 normals (3.1 +/- 0.1 mean +/- SEM vs 2.0 +/- 0.3%; p less than 0.01) but less than in three patients with pseudoxanthoma elasticum (9.7 +/- 0.6%; p less than 0.001). Desmosine radioimmunoassay (an index of elastic fibers) was greater in sickle cell disease patients with mitral prolapse than those without (239.3 +/- 9.3 vs 171.7 +/- 25.4 ng/mg wet weight; p less than 0.02). Histopathologic grading showed a similar trend (p = 0.07). The combined probabilities of these three independent tests of elastic fiber quantity showed an increased elastic fiber concentration in mitral prolapse patients compared to those without mitral prolapse (p less than 0.02). Thus, there is no evidence for a specific collagen defect; rather, sickle cell disease appears to be associated with a spectrum of elastic tissue disorders, a feature that could predispose to mitral valve prolapse.

Sickle cell disease and infection

Overwhelming infections caused by encapsulated bacteria, salmonella spp. and Plasmodium falciparum (in malarious areas) are an important cause of morbidity and death in patients with sickle cell disease. Bacterial infections afflicting these patients include fulminant meningitis and septicaemia caused by Str. pneumoniae and H. influenzae type b, and non-typhoid salmonellosis. Children less than five years of age are at greatest risk for meningitis and septicaemia, while salmonella osteomyelitis is probably common to all age groups. The most important contributing factors to this increased susceptibility to encapsulated bacteria are: a state of functional asplenia, an opsonophagocytic defect due to an abnormality of the alternative complement pathway, and a deficiency of specific circulating antibodies. Devitalisation of gut and bone due to repetitive vaso-occlusive crises, saturation of the macrophage system with red cell breakdown products of chronic haemolysis, and underlying splenic and hepatic dysfunction all predispose to salmonella infections. Seventy per cent of septicaemias and meningitis among under-fives with sickle cell disease is caused by Str. pneumoniae. Septicaemia frequently presents with sudden fever, few prodromal features, and a deceptive appearance of well-being, followed within hours by rapid relentless progression to shock and death. Adrenal haemorrhage is common, and mortality can be as high as 50 per cent, unless intravenous antibiotic, with or without steroid therapy, is promptly initiated. The clinical presentation of bacterial meningitis, its management and mortality follow the normal patterns, but recurrent meningitis and cerebrovascular morbidity are common in patients with sickle cell disease. An acute pulmonary involvement, indistinguishable from bacterial pneumonia (the 'chest syndrome') is the commonest single complication of sickle cell disease at any age. Str. pneumoniae is responsible for about half of the episodes. The protective values of the pneumococcal vaccine and long-term penicillin prophylaxis remain to be established in sickle cell disease. Over 70 per cent of haematogenous osteomyelitis in sickle cell disease is caused by salmonellae. The distinction from vaso-occlusive bone crisis is often difficult, but the presence of multiple, often symmetrical bone involvement, diaphyseal fissuring and involucrum should suggest osteomyelitis rather than bone infarction. Chloramphenicol remains the drug of choice and often has to be given in high doses for up to six weeks. The role of surgery is limited by the presence of multiple bone involvement and the known anaesthetic risks in this group.(ABSTRACT TRUNCATED AT 400 WORDS)

Long survival in sickle cell anemia

Ten patients with sickle cell anemia surviving beyond the age of 40 were compared to 11 subjects with sickle cell anemia who died before that age. Hematologic and biochemical data as well as clinical and physical parameters of the two groups were compared. There was no statistically significant difference between the two groups with respect to the degree of anemia, severity of hemolysis, or hemoglobin A2 levels. A statistically significant difference was found between the two groups with respect to fetal hemoglobin, red cell zinc, and secondary sexual characteristics. Although the long survivors had fewer crises per year than the short survivors, the long-term complications such as leg ulcer, congestive heart failure, and aseptic necrosis of the hip were more common in the older patients. Cerebrovascular accidents were the cause of death in 9/11 short survivors and are absent in the long survivors. The alpha/beta chain synthesis ratio was normal in the long-survivor group and alpha gene mapping in five subject in that group revealed the genotype alpha alpha/alpha alpha in four and -alpha/alpha alpha in one. The older patients as a group had higher red cell zinc values. The secondary sexual characteristics were also better developed in the older subjects. The overall significance of zinc status and of a higher HbF on longevity of sickle cell anemia patients remains unknown.

On the nature of sickle-cell disease in the Arabian Peninsula

The sickle-cell gene contributes substantially to the presentation of anaemia in certain areas of the Arabian Peninsula. However, the clinical presentation of the homozygous state of Hb S is less severe than that observed in other ethnic groups, such as American negroes. In the present paper, biosynthesis studies performed on reticulocytes from heterozygotes and homozygotes for the Hb S give further indications of the mild nature of sickle-cell disease in Arabia. Comparison of two affected families, from Saudi Arabia and Jordan, showed that clinical manifestation of the disease is mirrored by the biochemical and haematological findings in affected individuals. The results are discussed in terms of the effect of co-existing thalassaemia and/or iron deficiency with Hb S. It is suggested that both genetic and acquired conditions play a role in the clinical features of the disease. The mechanisms responsible for regulation of alpha-chain synthesis by iron (haem) deficiency are discussed.

Mild sickle-cell anaemia in Iran associated with high levels of fetal haemoglobin

Sixteen subjects, with sickle-cell anaemia, all Iranians (ages 3 to 56 years), with very mild symptomatology are reported. Some of the subjects had been totally asymptomatic. Splenomegaly was noted in 9 cases. There was an increase in the mean level of fetal haemoglobin (18%); this is the probable explanation for the mild phenotype. In 29 subjects with sickle-cell trait, the level of HbF was also significantly raised as compared with normal (1-6% vs. 0-6%). The mechanism of increased synthesis of HbF is unknown. The findings are similar to those reported in the Shiite Moslems of Saudi Arabia suggesting that in these populations there is a genetically-determined ability to produce high levels of Hb F in the presence of the sickle-cell gene.

Relatively benign sickle-cell anaemia in 60 patients aged over 30 in the West Indies

A study in Jamaica of 60 patients with sickle-cell anaemia over the age of 30 years showed that most of them were in full-time employment. Pains in the bones or joints, leg ulceration, and jaundice were the most frequent types of presentation, but only two patients had a haemoglobin level consistently below 6 g./ 100 ml. Most of the patients were well developed and of average height, and, though the development of secondary sexual characteristics was delayed, there was an average of 2.6 pregnancies per patient. These findings suggest that the course is more benign than has been realized.

Angioid streaks and elastorrhexis

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