Week 4 Flashcards
how does the sickling of RBCs appear
polymerisation of sickle Hb occurs
distorts the shape of RBC corpuscles
under deoxygenated conditions = sickling
how is motility shown between HbA and HbS
how are different Hb molecules are distinguished by..
electrophoresis
what is HbA
the normal dominant gene
what is HbS
the sickle gene - recessive
HbAS
sickle carrier - heterozygous
what makes up the normal adult Hb
two alpha globin chains
two beta globin chains
each with a haem group containing iron
what does foetal Hb contain
two globin
two gamma globin
each with a haem group
what is the mutation on HbS
a missense mutation on the 6th amino acid on the beta globin chain
where GAG becomes GTG
glutamic acid to valine
how is the HbS mutation detected
PCR
physiological effects of HbS mutation
repeated polymerisation of HbS
damages the RBC membrane
reduces RBC lifespan
from 120 to 10-20 days
what is vaso-occlusion
where sickled cells block blood flow
so tissues do not receive enough blood
occurs in narrow blood vessels
what are haemoglobinopathies
group of blood disorders caused by altered haemoglobins
categories of hamoglobinopathies
Hb variants and thalassemias
alpha thalassemia
deletion of alpha globin gene
beta thalassemia
mutation causes beta globin production
sickle alpha or beta thalassemia
shows mild SCD symptoms