haematology - inherited haemolytic anaemias Flashcards
inherited haemolytic anaemia membrane defects
hereditary spherocytosis
hereditary elliptocytosis
hereditary pyropoikilocytosis
pattern of inheritance of hereditary spherocytosis
autosomal dominant
hereditary spherocytosis deficiencies
membrane proteins
- spectrin
- ankyrin
hereditary spherocytosis is intra or extravascular?
extravascular
hereditary spherocytosis makes patients susceptible to
parvovirus B19
gallstones
hereditary elliptocytosis
autosomal dominant spectrin mutation leading to elliptical erythrocytes
hereditary pyropoikilocytosis
autosomal recessive
erythrocytes abnormally sensitive to heat
severity of hereditary elliptocytosis
ranges from hydrops foetal is to asymptomatic
inherited haemolytic anémia enzyme defects
G6PD deficiency
pyruvate kinase deficiency
role of G6PD
helps RBCs make glutathione for protection against oxidant damage
G6PD deficiency pattern of inheritance
X linked recessive
G6PD features which type of haemolysis
intravascular
features G6PD deficiency crisis
rapid anaemia jaundice dark urine bite cells Heinz bodies (blue deposits, oxidised Hb)
G6PD deficiency crisis triggers
oxidants drugs (2-3 days after starting) broad beans (<1 day of eating) acute stressors moth balls acute infection
drugs that may trigger G6PD deficiency crisis
primaquine
sulfonamides
aspirin
dx of G6PD deficiency made by
enzyme assay 2-3 months after crisis
take caution in G6PD enzyme assay because
young RBCs may have sufficient enzyme so results may appear normal
treatment of G6PD deficiency
avoid precipitants
transfusion if sever
genetic screening
splenectomy for chronic haemolysis
pyruvate kinase deficiency pattern of inheritance
autosomal recessive
autosomal dominant has been observed
features of pyruvate kinase deficiency
sever neonatal jaundice
splenomegaly
haemolytic anaemia
treatment of pyruvate kinase deficiency
most not required
blood transfusion
splenectomy
globin pairs and resulting type of haemoglobin
2 alpha + 2 beta = HbA
2 al[pha + 2 gamma = HbA2
2 alpha + 2 delta = HbF
SCD affects which type of globin
beta globin gene
alpha thalassaemia/HbH disease mutation
deletion of alpha globin gene
beta thalassaemia affects which type of globin
beta globin gene
sickle cell disease
pathological sickling of RBCs
SCD pattern of inheritance
autosomal recessive
sickle cell anaemia vs sickle cell trait
anaemia - HbSS severe
trait - usually asymptomatic except under stress
mutation causing sickle cell
single base mutation GAG -> GTG glu -> val at codon 6 of beta chain = HbS
sickle haemoglobin C disease
HbSC
HbC = defective beta chain
sickle beta thalassaemia
HbS/beta thalassaemia trait
age of onset of sickle cell anaemia
manifests at 3-6 months
coincides with decreasing HbF
features of sickle cell haemolysis
anaemia 60-80g/L splenomegaly folate deficiency gallstones aplastic crises
features of sickle cell vaso-occlusion and infarction
SICKLED
stroke infections (hyposplenism, CKD) crises (splenic, sequestration, chest and pain) kidney (papillary necrosis, nephrotic) liver (gallstones) eyes (retinopathy) dactilitis (impaired growth) mesenteric ischaemia priapism (long lasting painful erection)
sickle cell features onset in children
strokes
splenomegaly
splenic crises
dactylitis
sickle cell features onset in teenagers
impaired growth
gallstones
psych
priapism
sickle cell features onset in acdults
hyposplenism
CKD
retinopathy
pulmonary hypertension
dx of SCD
blood film - sickle and target cells
sickle solubility test
Hb electrophoresis
Guthrie test at birth
purpose of Guthrie test
performed at birth if SCD suspected to prompt pneumococcal prophylaxis
treatment of acute SCD crisis
opioid analgesia
blood exchange transfusion
top up transfusions in SCD crisis
can increase sickling
only use if Hb <60g/L
maintenance treatment of SCD
penicillin V
pneumovax
HIB vaccine
folic acid & hydroxycarbamide
regular exchange transfusions
carotid doppler monitoring with prophylactic exchange if turbulent
other treatment options for
crizanlizumab
allogeneic stem cell transplant
thalassaemia
unbalanced Hb synthesis
unmatched globins
haemolysis and ineffective erythropoeisis
beta thalassaemia
point mutations ↓ beta chain synthesis
excess alpha chains
↑ HbA2 and HbF
features of beta thalassaemia
skull bossing
maxillary hypertrophy
hairs on end skull XR
hepatosplenomegaly
B0 =
B+ =
B =
no expression of gene
some expression of gene
normal gene
beta thalassaemia minor
B+/B+ or B0/+
asymptomatic carrier
mild anaemia
beta thalassaemia intermedia
B+/B or B0/B moderate anaemia splenomegaly bony deformity gallstones
beta thalassaemia major
B0/B0 severe anaemia FTT hepatosplenomegaly (extramedullary erythropoiesis) bony deformity heart failure
dx of beta thalassaemia
Hb electrophoresis
Guthrie test at birth
treatment of beta thalassaemia
blood transfusions with iron chelation (prevent iron overload)
folic acid
minor/some intermedia may not need regular treatment
alpha thalassaemia
deletions causing:
↓ alpha chain synthesis
excess beta chains
alpha thalassaemia trait
1-2 deleted alpha chains
asymptomatic
mild anaemia
HbH disease
3 deleted alpha chains
moderate anaemia
splenomegaly
hydrops foetalis
4 deleted alpha chains
incompatible with life