G. Sanna

Iron overload and desferrioxamine chelation therapy in β-thalassemia intermedia

This study on serum ferritin levels ind urinary iron excretion after 12h subcutaneous infusion of desferrioxamine in 10 thalassemia intermedia patients shows that even nontransfusion-dependent patients may have positive iron balance resulting in iron overload from 5 years of age. However, the iron overload found in these patients appears to be much lower than in age matched patients with transfusion-dependent thalassemia major. Iron overload increases with advancing age, as shown by increasing serum ferritin levels and desferrioxamine-induced urinary iron elimination. After a six month trial of 12h continuous subcutaneous desferrioxamine administration there was a significant decline in serum ferritin levels.From this study it seems that iron chelation is indicated in thalassemia intermedia patients over 5 years of age in order to prevent iron accumulation. However, the appropriate treatment schedule should be tailored to the individual needs of each patients, established by close monitoring of serum ferritin levels and desferrioxamine-induced urinary iron elimination.

Auditory Involvement in Thalassemia Major

The auditory function of 75 children affected by homozygous beta0-thalassemia, managed with a low transfusion scheme and treated irregularly with low doses of desferrioxamine, and of 75 controls were examined. In 12 patients a mild bilateral conductive hearing impairment due to bony hypertrophy and/or adenoid hypertrophy was found. In 43 cases a moderate monolateral or bilateral sensory-neural hearing loss at high frequencies with recruitment phenomenon was observed. Ferritin levels were determined in a randomly chosen group of these patients with (14) and without heaing loss (11). In the subjects with sensory-neural hearing loss the mean ferritin levels were significantly higher than in those with no hearing defect. There was no obvious relation between sensory-neural damage on the one hand and Hb levels and unit of blood transfused on the other. The results of this study suggest that iron overload could be a cause of damage in the high frequency elements of the auditory mechanism. Intermittent hypoxia and slow 8th nerve compression due to bony hypertrophy as causes of auditory involvement are also discussed.

Serum ferritin, liver iron stores, and liver histology in children with thalassaemia.

Serum ferritin, liver iron stores, and liver histology were studied in 38 children with thalassaemia major who were being treated by regular blood transfusions. There was no correlation between serum ferritin levels and either the number of transfusions or the amount of iron deposited in the liver. However, for a given level of iron stores, ferritin levels were higher in patients with chronic hepatitis (including chronic aggressive and chronic persistent forms) than in those with hepatic siderosis only. We conclude that serum ferritin reflects tissue iron deposits in regularly transfused thalassaemic patients, only in the absence of hepatitis.

Agenesis of the corpus callosum, infantile spasms, spastic quadriplegia, microcephaly and severe mental retardation in three siblings

A sibship consisting of three siblings, one male and two females with unrelated parents, showed a clinical syndrome including: infantile spasms with hypsarrhythmia, microcephaly, severe mental retardation and spastic quadriplegia. The pneumoencephalogram performed in two sibs showed agenesis of the corpus callosum and aqueductal stenosis with tri‐ventricular dilatation. The disorder did not show a progressive course with deterioration of mental and neurologic functions. No biochemical or cytogenetic defect could be identified. Complement fixation for cytomegalovirus was negative. This syndrome complex is probably inherited as an autosomal recessive trait. The clinical and the genetic aspects of the syndrome are discussed.

Chronic Liver Disease in Transfusion-Dependent Thalassemia: Liver Iron Quantitation and Distribution

The quantitative and/or qualitative distribution of liver iron was assessed in 81 transfusion-dependent thalassemia major patients with chronic liver disease (36 with chronic active hepatitis, 23 with chronic persistent hepatitis, 22 with siderosis). Viral marker studies showed only 3 cases with both HBsAg and anti-HBc positivity in the serum, while the others had anti-HBc and anti-HBs or only anti-HBs or no B viral markers. A significantly higher iron overload was found in chronic hepatitis, particularly chronic active hepatitis, than in siderosis. The increased iron overload may be due to less intensive chelation treatment, higher intestinal absorption secondary to lower mean Hb levels, and/or to liver inflammation-dependent iron deposition. The liver iron overload in turn amy facilitate the development or persistence of chronic progressive liver disease.

Glucose-6-Phosphate Dehydrogenase Red Blood Cell Phenotype in GdMediterranean Heterozygous Females and Hemizygous Males at Birth

Summary: The distribution of red blood cell G6PD phenotype was studied by means of the methemoglobin elution test in newborn (46) and adult (50) GdMediterranean heterozygous females and newborn (20) and adult (30) hemizygous males. Newborn heterozygotes had a statistically significant (P < 0.0005) lower mean red blood cell G6PD enzymatic activity (3.23 ± 1.04) than did normal newborns (8.78 ± 1.91), whereas there was no significant difference (P > 0.30) from the mean of adult heterozygotes (2.93 ± 0.86). Like adults, newborn heterozygous females showed: (1) a clear correlation (P < 0.001) between the percentage of enzyme-deficient red blood cells and G6PD enzymatic activity; and (2) the expected two red blood cell population, i.e., one deficient and the other normal (mosaicism). However, in newborns, the distribution of the subjects according to G6PD-deficient red blood cell percentage (mean percent, 43.67) was significantly shifted (P < 0.025) in favour of the normal phenotype, unlike adult heterozygotes, who showed a symmetrical distribution of G6PD positive and negative red blood cells (mean percent G6PD-deficient red blood cells, 53.27; P > 0.20). Newborn hemizygous males showed a consistent percentage (average, 8.28 ± 2.2) of stained red blood cells due to the presence of young erythrocytes (pseudomosaicism) unlike the occasional stained cells (≤5) seen in adults. The prevalence of hyperbilirubinemia in hemizygous males and heterozygous females was 10.22 and 2.2%, respectively, whereas in G6PD normal newborns it was 5.1%. The practical implication of this study is that the diagnosis at birth of the heterozygous state for G6PD deficiency of the Mediterranean type may be more difficult than in adults. Therefore, very sensitive methods, such as the methemoglobin elution test, should be carried out.Speculation: Inasmuch as the distribution of GdMediterranean newborn heterozygous females according to the percent of G6PD-deficient red blood cells is significantly shifted in favour of the normal phenotype, the diagnosis at birth of the heterozygous state for G6PD deficiency of the Mediterranean type may be more difficult than in adults. Therefore, very sensitive methods for detecting enzymatic activity in individual red blood cells, such as the methemoglobin elution test should be used.

Interaction between the glucose-6-phosphate dehydrogenase deficiency and thalassaemia genes at phenotype level.

Summary. No significant differences were observed in the mean values of Hb A2 levels and red cell indices between G6PD‐ and G6PD+β thalassaemia carriers apart from the MCV, which was significantly higher in β thalassaemia G6PD‐ subjects, but still in the thalassaemia carrier range. No difference was seen between G6PD+ and G6PD‐α thalassaemia carriers. G6PD+β thalassaemia carriers show a significant increase in G6PD levels expressed as activity per g of Hb and to lesser extent as activity per number of red cells x 109; in G6PD+α thalassaemia carriers this increase is statistically significant only when the enzyme levels are expressed as activity per g of Hb. G6PD‐β thalassaemia carriers had enzyme levels higher than non‐thalassaemic G6PD‐ subjects only when the activity is expressed per g of Hb. G6PD activity was found to be increased in G6PD+ and G6PD‐ Hb H disease patients.

Chronic liver disease in transfusion-dependent thalassaemia : hepatitis B virus marker studies

The systematic screening of 253 children with transfusion-dependent homozygous beta-thalassaemia revealed a high incidence of hepatitis B virus markers. The highest frequencies of hepatitis B surface antigen (HBsAg) and antibody to hepatitis B core antigen (anti-HBc) were found in the group of patients with the smallest number of transfusions, while the highest frequency of antibody to hepatitis B surface antigen (anti-HBs) was detected in the patients who had had the largest number of transfusions. Follow-up of these patients showed (a) a high incidence of acute hepatitis B, which was mainly subclinical; (b) normal hepatitis B surface antigen clearance and normal antibody to hepatitis B surface development; and (c) a high frequency of increased transaminase values for over six months. In all the subjects with persistently high transaminase, histological examination revealed chronic persistent hepatitis or chronic active hepatitis. Apart from two cases of chronic active hepatitis with no B virus markers, and two cases of chronic persistent hepatitis with HBsAg and anti-HBc in the serum, all these subjects were anti-HBs positive but HGsAg and anti-HBc negative.

Iron chelation in transfusion-dependent thalassemia with chronic hepatitis.

In this study maximum urinary iron elimination with continuous desferrioxamine subcutaneous infusion was obtained in thalassemia major patients with chronic persistent or active hepatitis with lower doses (60 mg/kg) than those necessary in patients without hepatitis (80 mg/kg). Since dose-response curves were highly variable the treatment schedule should be tailored to the individual needs of each patient. Both groups may achieve iron balance but chronic hepatitis patients have more frequently a net urinary iron excretion. In patients with chronic hepatitis no correlation was found between serum ferritin levels or serum ferritin/aspartate aminotransferase ratios and transfusional iron overload while serum ferritin/aspartate aminotransferase ratios were seen to be correlated with liver iron stores.

Favism in GdMediterranean Heterozygous Females

Summary: Fifty-one girls, aged 2–10 yr, who had had hemolytic crises requiring hospitalization after the ingestion of fava beans, were randomly selected and examined for G6PD activity and percent of G6PD deficient red cells. The parents as well as 35 GdMediterranean heterozygous females who had never had significant hemolytic crises were also examined. GdMediterranean heterozygous females showed a G6PD activity of 2.58 ± 0.69 IU/gHb. The percent of deficient red cells was 60.09 ± 10.1 ranging from 45–85%. A clear correlation between the G6PD activity and percent of enzyme-devoid red cell was found. The distribution of the subjects examined according to the percent of G6PD deficient red cells is significantly shifted in favor of those whose percent of G6PD-red cells is higher than 50%. This is more conspicuous in subjects already hospitalized for a hemolytic crisis as compared to subjects who had never had hemolytic crises. In the group of girls hospitalized for a severe hemolytic crisis after ingestion of fava beans, we observed 39% homozygotes and 61% heterozygotes. Among the heterozygotes, only three subjects developed severe crises as to require transfusion. On the basis of the number of heterozygotes hospitalized for a hemolytic crisis and on the number of crises-free heterozygotes out of the population as a whole, we drew a probability curve showing the risk for G6PD deficient heterozygous females to develop hemolytic crises during childhood. This risk does not exceed an average of 1.3%.Speculation: The findings that G6PD deficient heterozygous females have a low probability of developing a significant hemolytic crisis during childhood and that such crisis is always moderately severe has a practical utility in genetic counselling and in the prescription of drugs that may be potentially harmful to G6PD deficient female heterozygotes.