Thalassemia: Genetic Counselling, Pedigree Analysis, and Overview

This assignment provides a comprehensive overview of thalassemia, a genetic blood disorder characterized by abnormal hemoglobin production and excessive red blood cell depletion, leading to anemia. It explores the inheritance pattern of thalassemia as an autosomal recessive disorder, differentiating between alpha and beta thalassemia based on the mutated gene. The assignment details the clinical presentation, including anemia, weakness, and organ enlargement, and outlines treatment approaches such as blood transfusions, iron chelating agents, and surgical interventions. Furthermore, it emphasizes the importance of genetic counseling in preventing thalassemia, explaining pedigree analysis to assess the risk of offspring inheriting the condition. References from Angastiniotis, Helmi, and others support the information provided, offering a detailed understanding of the disease, its management, and genetic implications.

THALASSEMIA: AN INHERITED DISEASE

Thalassemia: Overview
• Thalassemia is a genetic blood disorder.
• In this genetic disorder body of the affected patient produces a
distorted or abnormal form of hemoglobin.
• As a consequence, excessive depletion of red blood cells occur
in the affected patient. This further damages the transport of
oxygen and carbon-di-oxide by RBCs to different organs.
• This further leads to the development of anemia in the
affected patient.
• According to Global Burden of Disease Study 2013,
approximately 280 million people suffers from thalassemia.
• Thalassemia most commonly seen among people of Middle
East, Italian , African, Greek (Helmi et al. 2017).

Inheritance Pattern
•The inheritance pattern of thalassemia is
autosomal recessive.
•This type of inheritance pattern is rare in
populations.
• In this type of inheritance pattern, to
express the particular thalassemia
phenotype in an individual both copies of
allele should be mutated.
•Considering the fact that thalassemia is an
autosomal recessive disorder, in a
population, the prevalence of thalassemia
should be such that the number of
thalassemia-affected males should always
be equal to the number of thalassemia
affected females (Helmi et al. 2017).

Types of Thalassemia
•There are two different types of thalassemia;
alpha thalassemia and beta thalassemia.
•Alpha thalassemia occurs due to the mutation in
alpha globin component of hemoglobin.
Beta thalassemia occurs due to the mutation in the
HBB (hemoglobin beta) gene.
•Point mutations, nonsense mutations, frame shift
mutations in the coding sequence of alpha and
beta globin gene may often develop alpha
thalassemia and beta thalassemia respecticvely.
•Beta thalassemia is relatively more frequent
among Italian and Greek origin people. Therefore,
this type of thalassemia is popularly known as
Mediterranean anemia (Helmi et al. 2017).

Clinical Presentation of Thalassemia
Clinical presentation of thalassemia includes:
• Anemia- Reduced hemoglobin count.
• Weakness.
• Abnormal facial bones and reduced bone growth.
• Muscle fatigue
• Hepatosplenomegaly.
• Hb Bart syndrome.
• Frequent allergic infections.
• Heart defects may include tachycardia and bradycardia.
• Pale skin.
• Jaundice.
• Abnormal bleeding.

Treatment of Alpha Thalassemia
• Regular blood transfusions as well as folate supplements are
the two only principal treatments for treating alpha
thalassemia.
• Surgical treatment can also be done to treat alpha
thalassemia. Surgical treatment includes the removal of
spleen (splenectomy) (Helmi et al. 2017).
Treatment of Beta Thalassemia
•Treatment of beta thalassemia includes the use of iron
chelating agents as medication.
•Iron chelating agents are
a) Deferoxamine, b) Deferasirox (Helmi et al. 2017).

Genetic Counselling For Thalassemia
• Genetic Counselling- Genetic counselling is referred as the most
important and vital aspect of prevention. Genetic counselling is
intemately associated with genetic diagnosis . This, in turn,
increases people’s control of their own and their family’s health
(Angastiniotis 2013).
• Genetic counselling has been defined as: “The process by which
patients or relatives at risk of a disorder that may be hereditary are
advised of the consequences of the disorder, and the probability of
developing and transmitting it and the ways in which this may be
prevented or ameliorated” (Angastiniotis 2013).
• Genetic counselling plays an important role in preventing
thalassemia.

Pedigree Analysis
• In case of thalassemia affected patient, the carrier parents
have:
• 25% of offspring may develop diseased condition. It occurs as
two copies of the diseased (thalassemia) allele will be
inherited by offspring. As a consequence, offspring will have
thalassemia.
• 50% of offspring may develop diseased condition. As a
consequence, offspring will be considered as a carrier.
• 25% of the offspring will not inherit any diseased (thalassemia
affected) allele.

References
• Angastiniotis, M., 2013. Why prevention.
In Prevention of Thalassaemias and Other
Haemoglobin Disorders: Volume 1: Principles
[Internet]. 2nd edition. Thalassaemia
International Federation.
• Helmi, N., Bashir, M., Shireen, A. and Ahmed,
I.M., 2017. Thalassemia review: features, dental
considerations and management. Electronic
physician, 9(3), p.4003.