Biochemistry Hemoglobinopathies Study Notes
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Questions and Answers

What are hemoglobinopathies?

Hemoglobinopathies are diseases related to hemoglobin.

What are globin genes?

Globin genes are the genes that code for the globin proteins, which are the building blocks of hemoglobin.

The alpha globin gene family is located on chromosome 16.

True

What is the main difference between alpha and beta globin genes?

<p>Alpha globin genes are located on chromosome 16, while beta globin genes are located on chromosome 11.</p> Signup and view all the answers

What type of globin gene is primarily active in adults?

<p>Beta</p> Signup and view all the answers

Which of the following is NOT a type of hemoglobinopathy?

<p>Hemophilia</p> Signup and view all the answers

Hemoglobinopathies are primarily caused by...

<p>Genetic mutations</p> Signup and view all the answers

What are the two main categories of hereditary hemoglobin disorders?

<p>Qualitative and quantitative abnormalities.</p> Signup and view all the answers

Qualitative hemoglobin abnormalities affect the shape or function of hemoglobin.

<p>True</p> Signup and view all the answers

Quantitative hemoglobin abnormalities affect the amount of hemoglobin produced.

<p>True</p> Signup and view all the answers

What is sickle cell hemoglobin?

<p>Sickle cell hemoglobin (HbS) is a type of hemoglobin that is abnormal due to a mutation in the beta globin gene. This mutation causes the red blood cells to become sickle-shaped, leading to various health problems.</p> Signup and view all the answers

In sickle cell hemoglobin, glutamic acid is replaced by valine at position 6 in the beta globin chain.

<p>True</p> Signup and view all the answers

Sickle cell anemia is a disease caused by a mutation in the alpha globin gene.

<p>False</p> Signup and view all the answers

What are some factors that can increase sickling?

<p>Decreased oxygen pressure, increased carbon dioxide levels, decreased pH, and increased 2,3-bisphosphoglycerate (2,3-BPG) levels. This means sickling might occur in people with sickle cell trait when they are under stress or in low oxygen environments.</p> Signup and view all the answers

Individuals with sickle cell trait are clinically normal.

<p>True</p> Signup and view all the answers

What is hemoglobin C (HbC)?

<p>Hemoglobin C (HbC) is a type of hemoglobin that is abnormal due to a mutation in the beta globin gene. This mutation causes a substitution of lysine for glutamic acid at position 6, which results in a less severe form of hemolytic anemia compared to sickle cell anemia.</p> Signup and view all the answers

Hemoglobin C is less soluble than HbA.

<p>True</p> Signup and view all the answers

Hemoglobin C disease is generally less severe than sickle cell anemia.

<p>True</p> Signup and view all the answers

What is methemoglobinemia?

<p>A condition where the iron in hemoglobin is oxidized to the ferric state, making it unable to bind oxygen.</p> Signup and view all the answers

In methemoglobinemia, the iron atom in heme is in the reduced state (Fe²+).

<p>False</p> Signup and view all the answers

Methemoglobin reductase is an enzyme that converts methemoglobin back to hemoglobin.

<p>True</p> Signup and view all the answers

Mutations in the alpha or beta globin genes can affect the activity of methemoglobin reductase.

<p>True</p> Signup and view all the answers

What is thalassemia?

<p>Thalassemia is a group of inherited blood disorders characterized by a reduced production of either alpha or beta globin chains, leading to a reduced amount of hemoglobin and anemia.</p> Signup and view all the answers

Thalassemia is caused by a mutation in the globin gene.

<p>True</p> Signup and view all the answers

Alpha thalassemia is less severe than beta thalassemia.

<p>True</p> Signup and view all the answers

What is the most severe type of alpha thalassemia?

<p>Hydrops fetalis</p> Signup and view all the answers

What is hemoglobin H disease?

<p>Hemoglobin H disease is caused by a deletion of three of the four alpha globin genes. This leads to a reduced production of alpha globin chains and a higher proportion of a tetramer made up of four beta globin chains, known as HbH.</p> Signup and view all the answers

Beta thalassemia is usually less severe than alpha thalassemia.

<p>False</p> Signup and view all the answers

What is the main difference between alpha thalassemia and beta thalassemia?

<p>Thalassemia is a group of inherited blood disorders characterized by a reduced production of either alpha or beta globin chains, leading to a reduced amount of hemoglobin and anemia.</p> Signup and view all the answers

Alpha globin tetramers are soluble and do not cause premature destruction of red blood cells.

<p>False</p> Signup and view all the answers

Individuals with beta thalassemia minor usually require frequent blood transfusions.

<p>False</p> Signup and view all the answers

What is a pre-marriage test?

<p>A pre-marriage test is a genetic test that is designed to identify carriers of a specific genetic disorder, particularly in the context of marriage and family planning.</p> Signup and view all the answers

Pre-marriage testing is not recommended for individuals with a family history of thalassemia.

<p>False</p> Signup and view all the answers

What is hereditary persistence of fetal hemoglobin (HPFH)?

<p>Hereditary persistence of fetal hemoglobin (HPFH) is a benign condition where the switch from fetal hemoglobin (HbF) to adult hemoglobin (HbA) does not occur fully after birth, resulting in a continued production of HbF.</p> Signup and view all the answers

HPFH is a serious genetic disorder that requires medical treatment.

<p>False</p> Signup and view all the answers

What technique is used to differentiate between different types of hemoglobin?

<p>Electrophoresis</p> Signup and view all the answers

Electrophoresis can be used to identify carriers of thalassemia.

<p>True</p> Signup and view all the answers

Study Notes

Biochemistry Study Notes - Hemoglobinopathies

  • Hemoglobinopathies are diseases related to hemoglobin.
  • Globin genes produce globin protein first, followed by the heme group.
  • Hemoglobin has two gene families: alpha and beta.
  • The alpha gene family is located on chromosome 16 and has 2 genes for alpha-globin chains.
  • Other chains remain throughout life.
  • Each of these genes has 2 alleles (4 loci in total) for synthesizing hemoglobin.
  • The beta gene family is located on chromosome 11 and has a single gene for the beta-globin chain.
  • Chromosome 11 also contains 2 gamma and 1 delta gene.
  • Hemoglobinopathies are serious, inherited diseases - common worldwide.
  • About 5% of the global population are carriers, causing substantial morbidity.
  • Approximately 300,000 babies are born each year with hereditary disorders.

Qualitative Hemoglobin Abnormalities

  • Qualitative abnormalities affect the quality of the hemoglobin structure, leading to structural variants.
  • Sickle cell hemoglobin (HbS): an amino acid substitution in the beta subunit (Glu to Val) causes hemoglobin aggregation at low oxygen tension (PaO2 < 40 mmHg)
  • This aggregation causes red blood cell deformation, increased resistance to squeezing in capillaries, and blockage.
  • This leads to hypoxia, potential organ damage (e.g., kidneys, heart, lungs), and a shorter lifespan (<20 days) for sickled red blood cells compared to normal cells (120 days).

Quantitative Hemoglobin Abnormalities: Thalassemias

  • Thalassemias are caused by reduced production of alpha or beta globin proteins.
  • Alpha-thalassemia involves underproduction of alpha globin chains, affecting HbA, HbF, and HbA2.
  • Different levels of gene deletions vary the severity from asymptomatic trait to hydrops fetalis which is fatal.
  • Beta-thalassemia involves underproduction of beta globin chains.

Hemoglobin C (HbC)

  • A substitution in beta subunit (Glu to Lys) causes less soluble hemoglobin which crystallizes more easily than normal hemoglobin.
  • HbC is less severe than HbS, but still results in a minor hemolytic disorder.
  • HbSC disease arises when individuals have both beta-C and beta-S mutations.

Methemoglobinemia (HbM)

  • Methemoglobin occurs when iron in heme group is oxidized to Fe3+.
  • This reduced the ability of hemoglobin to bind to oxygen.
  • It can result from certain drugs like nitrates and can lead to blue baby syndrome.

Hereditary Persistence of Fetal Hemoglobin (HPFH)

  • Individuals with HPFH retain fetal hemoglobin (HbF) into adulthood; this is a benign variant.

Electrophoresis

  • A technique to identify different types of hemoglobin (normal, HbS, HbC) based on charge differences.
  • Different hemoglobin types migrate differently within the electrophoresis gel and can be identified by comparing their relative positions.

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Description

Explore the complexities of hemoglobinopathies, diseases associated with hemoglobin. This quiz covers the globin gene families, their genetic locations, and the impact of these inherited disorders on global health. Understand the qualitative abnormalities affecting hemoglobin structure and their implications.

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