Sickle cell disease Flashcards

1
Q

What is the sickle gene?

A

Sigle missense mutation at codon 6, leading to GLu repaplaced by val (non polar and smaller)
HbS results

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2
Q

What are the consequences of sickle cell gene on RBC?

A

Distrotion of RBC shape-polymerasition (initially reversible) with formation of OxyHbC-becomes irrevierible
ADherent, Rigid and Dehydrated (increase the OxyHbS)

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3
Q

Where is sickle gene most common?

A

Africa-especially west, but can be found to India (Might have risen independently - natural selection stronk)
matches endemic malaria
One of most common genetic disease

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4
Q

What is sickle cell disorder

A
SS aneamia (aneamia only for SS) and compoouns heterozygous states (SC, SB thalassemia)-genetically sumple (AR) but clinical heterogenous
Sickle cell disease encompaces all those variances
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5
Q

What is the effects of Sickle cell?

A

Short cell lifespan-heamolysis-aneamia, gall stones, aplastic crisis with parovirus (usually benign, but bad in SS)
Aneamia is partially due to reduced erythropoetic drive as HbS is low affinity Hb

Blockage of microvasculature-tissue damage, necrosis, pain(main cause of hosp), dysfunction. Infartion most common in spleen, bones (dactylitis) joints (osteomyelitis) skin (ulcers)

damages lungs (hypertension, chronic damage), urinary tract ( papillary necrosis, renal failure) , brain (stroke), eyes (retinopathy)

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6
Q

How does sickle cell disease cause microvasculature occlusion?

A

HbS form polymers in the cells and change the shape
Adherence to ICAM/VCAM and weird shape + rigidity causes blockages
Might also cause reduced NO bioavailability (SS cells scavenge it)

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7
Q

What are the causes of SS disease scavenging NO?

A

It causes numerous vasculopathy, including Polumonary hypertension -and these people usually have bad prognosis

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8
Q

How is the early clincal course of Sickle cell?

A

Can vary wildly, evem within the same famility
Symptoms are rare before 3-6 months-onset when swithc from fetal to adult Hb
Early-dactylitis, splenic sequestration, infections (s.pneumoniae)
Constant improvement of survival rates-like penicillin prophylaxis, help parents learn how to examine early staged
now most children live, but only till like 40/50

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9
Q

What are types of sickle emergency?

A

Speptic shock
Neurological signs - stroke (heamorghagic/ischeamic)
hypoxia (PoO2 <92%)
Signs and symptoms of aneaia (Hb<5)
Priapism-painful and lasting boner (can lead to permanent erectile dysf

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10
Q

What is acute chest syndrome with SSD?

A

Fever cought, chest pain, tachypnoae, chest pain
more common in SS>SS>SbThal
develop in vasculo occlusive crisis

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11
Q

What is avascular necrosis of the femoral head in SSD? and osteomyelitis?

A

Ischeamic damage to head of femur-lose the ball part

ALso common osteomyelitis due to salmonella infetions (most common, then staph)

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12
Q

What is stroke in SSD?

A

affects mostly SS -most common between 2-9 Y/o

Mostly middle cerebral and major arteries

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13
Q

What are gallstones in SSD?

A

By 25 y/o, prevalence is 50%

Coiheritance of guilbert syndrome increases risks further (less efficient bilibubin conjugation)

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14
Q

What are some laboratory features of sickle cell?

A
Hb low (6-8 g/dl), reticulocytes high (except in aplastic crisis)
Film-sickled, boat cells, target cells, Howel-jolly bodies
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15
Q

What are the methods for sickle cell diagnosis?

A

Solubility test-in the precesnce of reducing agent-solubility decrease, solition become turbid -but doesnt differentiate between SS and SA
Can also do Hb EPS/HPCL (high performancy liquid chromatography)

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16
Q

What are the general features of treatment options for sickle cell?

A

General measures-folic acid, penicilin prophylaxis, vaccination, monitor spleen size, transfusion for acute aneamia, acute chest syndr and stroke, prganancy care

Exchange transfusions for stroke/ACS
Heamotopoetic stem cell transplant-only for rare cases
Induction of HbF-hydroxyurea/carbomide and butyrate

17
Q

What are the treatment options for painful crisis of sickle cell?

A

pain relief (opiods, analgesia, NSAID, Pregabalin -but varies wildy between people, Most widely used is diamorphine), hydration, warmth, O2 is needed (need to find cause-PE0 -need to excluse infection (CXR and blood/urine cluture)

18
Q

What are the main causes of sickle cell painful crisis?

A

Hypxoia, psycho stress, dehyrdation Infections, exercsions, exposure to cold

19
Q

what are the main disease modifying treatments for SSD?

A

hydroxyCardbomide (increase HbF, leading to less problems), transfusions and Heamatopoetic stem cell transplant

20
Q

What are the indications for heamatopoetic inSSD?

A

Usually for children where hydroxyurea has failed and they have CNSissue or ACS

21
Q

What new therapy are underway?

A

sucessful gene thearpy has converted SS to AA

P-selectin inhbitor-mAb Crizanlizumab - reduce the adherence of SSRBC in microvasculature

22
Q

What is sicke cell trait?

A

HbAS
normal life epxentency, normal blood count-asually asymptomatic
rarely-painless heamaturia
Can be problem in aneastetis, high altitude and extreme exertions (can even cause sudden death if bad enough)