1. molecular medicine Flashcards
define a single nucleotide polymorphism
single nucleotide difference (substitution) in the genome at a specific position. It is present in a sufficiently large proportion of the population – may increase risk for multifactorial disease
how single nucleotide alteration in DNA can result in a structural and functional change for haemoglobin S in sickle cell anaemia
base change from T to A, The change in base sequence of the DNA results in a codon of the mRNA being altered during transcription. This fault results in a different amino acid (Valine) being inserted into the protein chain during translation. The presence of valine in the protein makes the deoxygenated haemoglobin less soluble. So when haemoglobin losses its oxygen the molecules come out of solution and crystallise into rod like structures. This distorts the normal circular shape of the red blood cell, causing them to a take a rigid, sickle shape.
what is hepatomegaly
to counteract the effects of anaemia from SCD, the red blood cells are produced outside of the bone marrow – usually in the liver – which can lead to hepatomegaly (abnormal enlargement of the liver)
how does sickle cell anaemia lead to symptoms
primary symptoms: anaemia and the tendency for the red blood cells to change shape rendering them useless. The sickle cells have a tendency to jam in capillaries and small blood vessels preventing normal blood flow as show in the image below.
The blocking of the blood vessels results in secondary symptoms: severe pain to the arms, leg, back and stomach. Joints can become stiff and hands and feet may swell. Individual suffering from sickle cell anaemia may show poor signs of growth and development and are prone to infections and strokes.
Can get stuck in cerebral vessels and can lead to stroke Blood vessels constrict when it is cold so symptoms can worsen, red blood cells can clump
