Hemoglobinopathies

what is hemoglobinopathy?

abnormally formed or diseased hemoglobin

a typical hemoglobin found in adults is a mix of

predominantly hemoglobin A, a little bit of hemoglobin A2 (A2delta2), and a tiny bit of fetal hemoglobin (A2gamma2)

everyone has ____________ types of hemoglobin in our body

multiple

there are over _______ different mutations of the globin chains in human hemoglobin

1000

what is thalassemia

group of related diseases that are inherited and are due to atypical genetic coding for the globin chains in hemoglobin

severity of thalassemia depends on what

how many of the genes are missing for either alpha globin or beta globin

thalassemia has been thought to have arisen to protect against what

malaria

what is alpha thalassemia

lack or absence of alpha globin chains

what might people with alpha thalassemia have or experience

severe: severe anemia, die in utero

mild: mild microcytic anemia or asymptomatic

what is the mildest form of alpha thalassemia called

alpha thalassemia trait

what happens to the beta globins in someone with alpha thalassemia

beta globins form unstable tetramers called hemoglobin H (does not work as efficiently)

what is beta thalassemia

lack or absence of beta globin chains

what might people with beta thalassemia have or experience

major: profound anemia and dependent on transfusions to live

minor: microcytic anemia or asymptomatic

what is the most common anemia in the USA

iron-deficiency anemia

in iron deficiency anemia, the RBCs are

small; microcytic

why can beta thalassemia minor and alpha thalassemia trait both be confused with iron deficiency anemia

all 3 conditions manifest with a microcytic anemia

why should people with thalassemia not take iron supplements long term

iron will not help their anemia and can result in iron overload

what should you do if patients who are taking iron do not see improvement in their anemia

more evaluation such as a hemoglobin electrophoresis

what is sickle cell disease caused by

autosomal recessive genetic modification of the beta globin gene

hemoglobin S modification is partially protective against what

malaria

what happens in sickle cell disease

RBCs reshape in hypoxic situations

what can happen when the misshapen cells circulate

they can cause vaso-occlusion which is extremely painful

what can vaso-occlusive events cause

extremely painful episodes and serious organ system complications

why are vaso-occlusive events painful

due to the blocked blood flow, the hypoxia problem is worsened as blood cannot get to the tissues; and the low oxygen tension also leads to hemolysis of the RBCs

what is ischemia

low blood flow

what can happen to people with SCD from these ischemic episodes

tissue infarction (cell death); multiorgan failure and death

in SCD, what kind of mutation occurs in the beta globin gene

one point mutation that causes the chains to contort to flatten the RBC when triggered

the hemoglobin in SCD is known as

hemoglobin S

people with 2 homogenous ends for SCD will have _____ episodes that someone who is heterozygous

worse

many people with SCD have a second gene for _________

different hemoglobin other than hemoglobin A

what 9 things are associated with sickle-cell disease

1) chronic anemia

2) chronic pain

3) neurological complications

4) pulmonary complications

5) renal impairment

6) osteoporosis

7) cardiomyopathy

8) hepatotoxicity

9) venous thrombosis

much of treatment for SCD is what

supportive; aims to avoid vaso-occlusive episodes

what are 4 other treatments for SCD besides pain management

1) immunizations are imperative

2) hydroxyurea which increases fetal hemoglobin

3) anticoagulants

4) blood transfusions