July 2023
Monthly Digital Case Study
June 2023 QSP Slides
Hemoglobinopathies - Part 2
Quiz
(PDF for print)
June 2023 QSP Slide 5:
FBC Results | |||
| WBC | 6.35 (10^3/mm3) | Neutrophils | 53% |
| RBC | 3.41* (10^6/mm3) | Lymphocytes | 19.9% |
| HGB | 14.2* (g/dL) | Monocytes | 21.3% |
| HCT | 30.7* (%) | Eosinophils | 5.1% |
| MCV | 90 (fL) | Basophils | 0% |
| MCH | 41.6 (pg) | ||
| MCHC | 46.3 (g/dL) | ||
| PLT | 363 (10^3/mm3) | ||
Clinical Details:
05 June 2023, Male (64 years old)
Slide Information:
Red blood cell flags. Agglutination of red blood cells (+++) due to the presence of a cold agglutinin verified after incubation of the sample at 37°C and rerun of this sample to check the results associated with the parameters which were alarmed.
Expert Comment:
Look for a cold agglutinin. Cold agglutinin disease/lymphoproliferative syndrome?
The most significant hemoglobinopathies result in either a change in the structure and quality of the hemoglobin, or a reduction in the quantity of hemoglobin produced.
Hemoglobinopathies are:
• not gender (x) linked
• more prevalent in some parts of the world
The likelihood of a person being a carrier of a hemoglobinopathy depends on ancestry. The type of mutation varies between ethnic groups. It is possible to inherit mutations in both alpha and beta globin genes at the same time. It is also possible (although rare) for an individual to have a ‘de novo’ hemoglobin mutation. This is a genetic mutation that is not directly inherited from parents but is present only in that individual.
The genes to produce hemoglobin are inherited from both parents. Sickle cell disease or beta thalassemia major are recessively inherited. If one unusual beta chain gene is inherited from one parent, the individual will be a carrier of the condition but will not be affected. This is known as having a trait. Carriers of hemoglobin variants are healthy and are unaware of their status unless detected during screening.
Should two unusual beta chain genes are inherited (one from each parent), the individual will have a hemoglobin disorder. The most common clinically significant conditions are beta thalassemia major and sickle cell disease.
If both parents carry a significant hemoglobinopathy, the baby is at risk of inheriting a hemoglobin disorder. There is a:
• 1 in 4 (25%) chance of being completely unaffected
• 2 in 4 (50%) chance of being a carrier
• 1 in 4 (25%) chance of inheriting the condition:
If a person inherited one normal haemoglobin A gene and one sickle haemoglobin gene, they are a sickle carrier. With one typical haemoglobin gene and one altered form of the gene, people with the sickle cell trait make both typical haemoglobin and sickle cell haemoglobin.
Their blood might contain some sickle cells, but they generally don't have symptoms. They're carriers of the disease, however, which means they would pass the gene to their children.
Sickle cell disease occurs when a person inherits two abnormal copies of the β-globin gene (HBB) that makes hemoglobin, one from each parent. This gene occurs in chromosome 11. Several subtypes exist, depending on the exact mutation in each hemoglobin gene.
Sickle cell disease most commonly affects people of West African, Caribbean, Middle Eastern and Indian ancestry. However, it can affect anyone from any population.
Sickle rbc’s have a shorter than average life span (10-20 days), and this premature destruction results in anemia. Unlike normal rbc’s which are flexible, sickle cells are rigid and also sticky. This can cause clumping in vessel walls, resulting in obstruction and a reduced oxygen supply to various organs. This occurs frequently and manifests itself as periodic episodes of pain, known as “crisis”. These Vaso-occlusive events can result in damage to eyes, kidneys, and lungs.
Normal red blood cells
Sickle red blood cells
As the spleen is managing increased numbers of dead rbc’s, it becomes fibrous and enlarged. The immune function in the spleen declines, which results in the individual being more susceptible to infection. The hyposplenism would be indicated by the presence of Howell-Jolly bodies and target cells. In an attempt to compensate for the rbc loss, the bone marrow attempts to produce more cells and grow larger. This results in weakened bones. Patients also present with jaundice due to the rapid destruction of heme in the rbc’s.
What feature can be seen in the red cell?
A) Basophilic Stippling
B) Bitten Out Cell
C) Cabot’s Ring
Basophilic Stippling or punctate basophilia describes the presence of numerous small basophilic inclusions in the cytoplasm of the red cell. They are composed of aggregates of ribosomes, degenerating mitochondria and siderosomes. Basophilic Stippling is associated with conditions such as thalassemia, hemolytic anemia, myelodysplastic syndromes, sickle cell anemia, heavy metal poisoning (lead, zinc, arsenic, etc.)
Bibliography
https://medlineplus.gov/lab-tests/hemoglobin-electrophoresis/
Essential Haematology, A.V .Hoffbrand & J.E.Pettit
https://www.mayoclinic.org/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1390791/
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