Paediatrics A Unit Prof. Dr. P.L. Siddaraju

By Dr. Nithyanand Patil

• Thalassemia was first described by Cooley in 1925 as “a hereditary hemolytic anemia with characteristic frog-like or mongoloid facies, skeletal changes and splenomegaly”.

Whipple & bradford coined the term ‘Thalassemia’- meaning ‘The sea in the blood’ (Mediterranean)

hemoglobins The list shows their globin chains The alpha chains are identical in each Every chain has a similar structure They vary in some of the amino acids The percentages are those seen in the adult.

is controlled by a separate gene. Genes are listed with the number inherited from each parent and the chromosome on which they lie. There are two different gamma genes (and chains) that differ by one amino acid - a matter of little clinical significance.

The gamma, delta and beta genes lie next to each other on chromosome 11. The two alpha genes lie next to each other on chromosome 16.

HEMOGOLOBIN PERCENTAGES ADULT vs NEWBORN This list shows the percentage of each normal hemoglobin in the adult and newborn. An "adult" as far as hemoglobins are concerned is any child over the age of one year! The switch in percentages occurs as a result of an increase in beta chain production and a decrease in gamma chain production beginning at the 6th month of fetal life. Delta chain production is minimal at birth and reaches normal levels (about 3% of total) at about one year of life.

HEMOGLOBIN DEECTS The three main types of hemoglobin defect are listed here. Since all are very common combinations are al so common. INHERITANCE PATTERNS This diagram shows the inheritance pattern of one (Hb S) and of two (Hb S and Hb C) beta chain structural defects. These are relatively simple because there are only two beta chain genes. The situation is much more complicated in the case of alpha chains because two alpha genes are inherited from each parent, giving a total of four.

THALASSEMIA The thalassemias are a widespread collection of genetic disorders in which there is an imbalance in globin chain production -- almost always a decrease or absence of production of one or rarely two globin chains. They are named according to the chain that is decreased.

alpha thalassemia-very common affects Hb A, Hb A2, and Hb F production.

beta thalassemia-common-affects Hb A production delta-beta thalassemia fairly common-affects Hb A and Hb A2 production delta thalassemia-rare affects Hb A2 production. Clinically unimportant gamma thalassemia-rare-affects Hb F production in fetus

Thalassemia definitions The more severe the imbalance between for instance alpha and beta chain production the worse the disease.

The terms major and minor etc are now only used as clinical (or severity) descriptions.

Major used to be synonymous with homozygous. Minor used to be synonymous with heterozygous. thalassemias since there are only two beta genes whereas with four alpha genes there can be four abnormalities. depending on whether one, two, three or four genes are affected.

ALPHA THALASSEMIA A brief comparison of the clinical effects and the proportions of Hb H and Hb Barts when one, two, three, or four genes are deleted is shown in this Table. When alpha chain production is reduced, the excess beta and gamma chains can each form tetramers (Hb H and Hb Barts). The excess alpha chains in the beta thalassemias do not form tetramers.

•Patho Physiology of Thalassemia

•

a.

Types of β-Thalassemia:

Homozygous b.

Hetrozygos c.

Intermedia β-Thalassemia, Homozygous Forms (Major and Intermedia)

Pathogenesis

1.

Variable reduction of β-chain synthesis (β˚, β  , and 2.

variants.

 -Chain excess results in intracellular percipitation of insoluble  -Chains.

3.

Increased but ineffective erythropoiesis with many red cell precursors prematurely destroyed is related to  Chain excess.

4.

Shortened red cell life span and variable splenic sequestration.

Sequelae 1. Hyperplastic marrow: bone marrow expansion with cortical thinning.

2. Increased iron absorption and iron overload (especially with repeated blood transfusion) resulting in the following pathology: a. Cirrhosis of the liver b. Endocrine disturbances, e.g., diabetes mellitus c. Skin hyperpigmentation d. Cardiac hemosiderosis 3. Hypersplenism

Clinical Features

1.

2.

3.

Failure to thrive in early childhood: common presentation Anemia Jaundice, usually slight; gallstones 4.

5.

Hepatosplenomegaly, which may be massive; hypersplenism Abnormal facies, prominence of malar eminences, frontal bossing, depression of bridge of the nose, exposure of upper central teeth.

a. Skull radiographs showing hair-on-end appearance caused by widening of diploeic spaces b. Fracture resulting from marrow expansion and abnormal bone structure c. Generalized skeletal osteoporosis 6. Growth retardation: primary amenorrhea in females; delayed puberty in males caused by chronic anemia and endocrine disturbances 7. Leg ulcers 8. If untreated, 80% die in the first year of life

Note hepatosplenomegaly

The children show mongoloid facies characterized by bossing of the skull, prominent frontal and parietal eminences, with flattened vault, straight Forehead, hypertrophy of maxilla, prominent malar eminences, depressed bridge of the nose and puffy eyes.

Complications Complications develop as a result of these situations: Inadequate treatment in the first years of life so that some irreversible damage occurs Poor compliance Excessive blood consumption Insufficient energetic application of chelation therapy Even in carefully managed patients, the following complications may develop: 1. Endocrine disturbances (e.g., retarded growth, delayed puberty, insulin dependent diabetes, hypogonadism, adrenal insufficiency, hypothyoidism, hypoparathyroidism).

2. Cirrhosis of the liver and liver failure.

3. Cardiac failure caused by anemia, increased plasma volume, and myocardial iron overload. Is often associated with arrhythmia, pericarditis.

4. Spinal cord compression is caused by epidural extramedullary hematopoiesis. Surgical excision of epidural mass and radiotheraphy in a dose of 2,000-3,000 cGy is recommended.

Laboratory Investigations

The level of Hb is  . It is usually between 2 and 6 g/dL. Fetal Hb level is  while HbA2 is normal.

Cells  Total erythrocyte counts are  and usually range between 2 to 3 million/mm³. Hematrocrit is  . MCV and MCH or MCHC are  . Reticulocyte count appears  .  in % of reticulocytes is not as high as the cells are destroyed in the marrow before they are released as reticulocytes. There is mild leucocytosis and thrombocytosis due to prolonged stimulation of the bone marrow.

Peripheral Smear.

Red cells show hypochromia, anisocytosis and poikilocytosis. Many microcytes and occasional macrocytes with a variable number of target and tear drop cells are seen. There is marked basophilic stippling and variable polychromasia. Fragmented red cells, nuclear remnats like Howell Jolly bodies, and Heinz bodies may be seen. A large number of early, intermediate and late erythroblasts are the most characteristic findings in the P/S.

Thalassemia Major Thalassemia Minor

Bone marrow

. The bone marrow is hypercellular with erythroid hyperplasia with a increased number of stippled erythroblasts and sideroblasts. Granulopoiesis and thrombopoiesis are relatively preserved. Hemosiderin deposits in the marrow are increased.

Osmotic fragility

. The fragility of the cells on exposure to hypotonic saline is decreased. The cells being thinner than usual can absorb more water before bursting. Hemolysis may continue till they are incubated with 0.2 percent saline and it may not be complete even in distilled water.(NESTROF TEST +VE).

Serum bilirubin

level is moderately  between 1 to 3 mg/dl. This depends on the rate of hemolytic activity, functional capacity of the liver to excrete the bilirubin and the mass of hemoglobin available for hemolysis. Urinary excretion is markedly  . There may be evidence of progressive liver dysfunction.

Serum iron

levels are high as a result of increased iron absorption, ineffective utilization and release of iron from continuous hemolysis of red cells. Iron binding capacity is  .

Serum ferritin levels are markedly raised which reflect total iron stores. Level of the fetal Hb and HbA2 may be Hb level get   . Fetal following transfusion and thus be diagnosis of thalassemia may become difficult. HbA2 levels are normal or slightly raised. Free erythrocyte porphyrin level is normal.

51 Chromium labelled red cell life span is reduced.

Liver Function Test – SGOT/SGPT are altered.

Hemoglobin electrophoresis: Cellulose acetate pH 8.4,Citrate agar pH 6

ELECTROPHORESIS Electrophoresis is a means of separating hemoglobins. It depends on the migration of the hemoglobin molecules dissolved in a buffer on, or in, a supporting medium when an electric current is passed through them.

Radiological changes in thalassemia

Earliest bony changes occur in the small bones of the hands which show a rectangular appearance. Medullary portion of the bone is widened and the bony cortex is thinned out with a coarse trabecular pattern in the medulla.

Diploid spaces in the skull are widened. As these traverse between the bone trabeculae in the outer table of the skull, the latter looks atrophied. Interrupted porosity gives hair on end appearance in X ray film of the skull.

History  Race Family History  Clinical Examination  Age of Onset Pallor Jaundice Splenomegaly Skeletal Deformity  Blood Count and Film  Pigmentation Hb MCV MCH Retics RBC Inclusions in Blood or Marrow a  Hemoglobin Electrophrosis  Hb A2 and Hb F Estimation   b  c Hb H Precipitation Presence of Abnormal Hb to include Analysis at pH 6-7 for Hb H and Hb Barts To confirm  Thalassemia Intracellular Structural Distribution Globin-Chain Analysis of Hb Variants.

Of Hb F Synthesis

Management

1. Hypertransfusion protocol† to maintain a pretransfusion Hb between 10.5 and 11.0 g/dl at all times using the following: a. Washed or leukocyte-filtered, packed red cells to avoid antileukocyte antibodies. The post-transfusion Hb should not rise above 16 gm/dl because higher levels cause an increase in blood viscosity, increased risk of thrombosis, and reduced tissue oxygenation.

b. Blood that closely matches patient’s genotype to avoid antibody formation.

c. Blood should be started when diagnosis is made and the Hb levels falls below 7 g/dl and remains there for a week or more Hypertransfusion results in the following: a. Growth and development are maximised.

b. Extramedullary hemotrpoiesis is minimized thereby decreasing facial and skeletal abnormalities.

c. Excessive iron absorption from gut is reduced.

d. The development of splenomegaly and hypersplenism is retarded because it reduces the number of red cells containing  -chain precipitates that reach the spleen.

2. Chelation therapy a. Objectives: (1) To remove excess intracellular iron (2) To bind free extracellular iron (3) To reduce iron burden to minimal levels b. Iron overload results from the following: (1) Increased gut absorption of iron (2) Chronic hemolysis (3) Ongoing transfusion therapy c. Chelation is attained with the use of Desferrioxamine in the following way: (1) Chelation is started more or less at the same time as starting transfusions.

(2) Continuous subcutaneous infusion in a dose of 40 mg/kg/day over 8-10 hours nightly via portable electronic pump plus 100 mg of vitamin C orally results in considerable iron chelation and delays development of iron overload and cirrhosis.

(3) In selected cases, with severe iron overload, give desferrioxamine IV in high dose, maximum 100 mg/kg over 8 hours, on the days of transfusion.

(4) The aim is to maintain serum ferritin close to 1,000 ng/ml, which should be monitored every 6 months.

d. Complications of Desferrioxamine administration: (1) Local painless swelling at infusion site. Decrease the concentration of the solution infused by increasing the amount of water used with a given dose.

(2) Local reactions: pruritus, rash, hyperemia. Add hydrocortisone 2 mg/ml to Desferrioxamine solution.

(3) “Anaphylactoid” reactions: treat by desensitization.

(4) Toxic effects on the eye: cataracts, reduction of visual fields and visual activity, an night blindness occurs with prolonged or high dose theraphy and regress when treatment is suspended.

(5) Hearing impairment occurs only with prolonged or high dose therapy.

Deferiprone

(DFP) is an effective oral iron chelating agent with minimal toxicity. It is given in a dose of 75-100 mg/kg/day in 2-3 divided doses. The most common side effect is arthropathy. Agranulocytosis is rare toxicity.

Neocyte transfusion.

Special cell separators are available for obtaining younger cells with longer life span (

neocytes

).

Infusion of these cells instead of the whole blood increases the interval between two transfusions and decreases the transfusion requirement and hence the iron load.

3. Splenectomy a. This procedure reduces transfusion requirements in patients with hypersplenism.

B. Prophylatic pneumococcal and hemophilus influenza B vaccine 2 weeks before splenectomy and prophylactic penicillin 250 mg BID life-long post splenectomy are given to reduce the risk of overwhelming postsplenectomy infection. Whenever possible splenectomy should be postponed until after the fifth year of age. c. Indications for splenectomy: (1) Persistent increase in blood transfusion requirements by 50% or more over initial needs for more than 6 months.

(2) Yearly packed cell transfusion requirements exceed 250 ml/kg/year (3) Evidence of severe leukopenia and/or thrombocytopenia.

4. Leg ulcers

Leg ulcers are very difficult to treat. Patients should take the following measures: a. Wear a toweling band round the ankles.

b. Sleep with end of bed raised 10 cm.

c. Keep legs and feet raised for 1 to 2 hours during the day d. Take zinc sulfate by mouth e. Oxygenate the ulcers 5. Supportive care a. Folic acid is not necessary in hypertransfused patients; 1 mg daily orally is given to untransfused (intermedia patients).

b. Hepatitis B vaccination should be given to all patients.

c. Digitalis and diuretics are given when indicated for congestive heart failure.

d. Endocrine intervention, i.e., L-thyroxine growth hormone, estrogen, testosterone, are given when indicated.

e. Cholecystectomy is advised when evidence of gallstones occurs.

f. Genetic counselling and antenatal diagonis via chrionic villus sampling or amniocentesis are suggested.

6. Follow-up of patients with thalassemia: Prior to treatment Study the case and do complete Before each transfusion: red cell typing Hb, crossmatch and red cell antibody detection, and serum transfaminases (in areas with a high incidence of hepatitis) are performed. Record the date of transfusion, net weight and After each transfusion: mean hematocrit of the blood preparation, and the Hb of the patient.

Measure the post-transfusion Hb

Every 3 months: Every 6 months: Every year: Variable intervals: Measure height and weight Estimate ferritin Evaluate growth and development. Evaluate iron balance. Complete evaluation of the case including: > Cardiac function > Endocrine function > Monitoring visual and auditory activity > Viral serologies Cardiac and endocrinological investigations according to the clinical state of the patient

7. Future directions a.

Oral chelators. Clinical testing of a number of oral chelating compounds is under way. 1,2-Dimethyl 1-2-hydroxypyrid one (L1) in a dose of 75 mg/kg/day orally has comparable efficacy to subcutaneous Desferrioxamine and may soon be available for clinical use in the United States. Controversy exists at present about its potential toxicity.

b. Pharmacologic upgrading of fetal Hb synthesis (1) High levels of fetal Hb (HbF) ameliorate the symptoms of  -thalassemia by increasing hemoglobinization of the thalassemic red cell and decreasing the accumulation of unmatched  -chains, which cause ineffective erythropoiesis.

Gene Manipulation  -chains by  -chains which combine with  -chains to form HbF (2) Trials are in progress with several agents that increase HbF synthesis: (a) 5-Azacytidine (b) Hydroxyurea (c) Cytosine arabinoside (d) Busulfan (e) Butyrate These agents can decrease or eliminat transfusion dependence, but side effects include neutropenia, increased susceptibility to infection, and possible tumorgenicity.

c.

Bone marrow transplant

(1) Marrow transplantation from an HLA-identical sibling is a curative mode of theraphy.

(2) The greater the degree of hepatomegaly, hemosiderosis, and portal fibrosis of the liver before transplant, the worse the outcome.

(3) A reasonable approach would be to employ allogeneic BMT at the earliest signs of hepatic enlargement or portal fibrosis, if a suitably matched donor is available.

(4) Bone marrow transplantation is a controversial mode of therapy because its risks must be weighed against the fact that patients who are least symptomatic have the best transplant results. The following information is available about transplantation: (a) Results are better among patients younger than 3 years who have received few transfusions and are without significant complications.

(b) Graft-versus-host disease (GVH) occurs less frequently in younger patients.

(c) The refinement of methods of preparation for transplantation have brought about a drastic reduction in mortality.

d. Heart Transplant

Heart transplant has been successfully carried out in thalassemia and should be considered in severe hemochromatotic myocardiopathy with cardiac failure in the absence of cirrhosis.

e. Gene Therapy

(1) Insertion of normal globin genes into marrow stem cells may ultimately cure thalassemic syndromes.

(2) The practical application of this technique is not feasible in the near future.

Thalassemia Control

Marriage Counselling Prenatal Diagnosis

can be made from fetal blood by determining the  vs.  -chain ratio. A ratio of <0.025 is suggestive of thalassemia major and needs MTP.

Molecular diagnosis

can be made by study of different loci of  globin gene by RFLP & PCR.

Amniocentesis CVS