genetics Flashcards
investigations
chorionic villus sampling
amniocentesis
pre-implantation genetic diagnosis
gamete donation
Duchenne muscular dystrophy
o X-linked recessive trait (Mother carrier)
o Fatal in early adult life
o Carrier testing
Gowers’ sign
Autosomal dominant conditions
one parent affected, no skipped generations
Down syndrome screening-
triple screening measures serum levels AFP, oestriol and beta hCG screen for
Patau, Edward, Down
Nuchal Translucency & Pregnancy associated plasma protein PAPP-A + free beta HCG
Selection for amniocentesis
free fetal DNA
Cystic fibrosis
defect of cellular chloride transport channels
Meconium Ileus
pancreatic insufficiency
recurrent lung infections: acute/ chronic
o Diagnosis: Immunoreactive trypsin (first 6 wks), sweat test, genotyping
o More than 1000 gene mutations cause disease
o Some of these particularly common- enables genetic diagnosis, screening, prenatal diagnosis
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sickle cell disorders
o Sickling
♣ Pain+++
♣ Cold, dehydration, infections
♣ Jaundice, stroke, leg ulcers, eyes, kidneys
♣ African, Mediterranean, Middle-East, Indian
♣ Anaesthetic issues
tay sachs disease
-progressive, genetic, lysosomal storage disease
hexosaminidase A deficiency results in build up of lipid especially jn brain
Baby usually develops normally until about 6 months of age. Progressive neurological deterioration. Usually fatal by 3-5 years
Phenylketonuria
o Autosomal recessive condition – biochemical screen, carriers not identified
o Babies with PKU are unable to break down phenylalanine (an amino acid in protein)
o Untreated babies develop serious, irreversible, mental disability
o Early treatment with a strictly controlled diet (exclude phenylalanine) prevents disability
o Treatment should start by 21 days of age
congenital hypothyroidism
o 1 in 4,000 babies in UK
o 1 in 10 cases inherited – hormone test, carriers not identified
o Untreated babies -> serious, permanent, physical and mental disability
o Early treatment with thyroxine tablets prevents disability
Treatment should start by 21 days of age
medium chain acyl CoA dehydrogenase deficiency
o Recessive inherited condition – carriers not identified
o Babies with MCADD cannot easily break down fat to make energy for the body
o Serious life-threatening symptoms can occur quickly in babies not feeding well or unwell
o Mean age at first presentation is 14 months. 25% mortality rate
o Treatment to prevent metabolic crisis:
♣ Avoid fasting and monitor frequency of meals
o Emergency regime: glucose polymer (maxijul) and IV dextrose
Glutaric aciduria type 1
o An inherited disorder in which the body is unable to break down completely the amino acids lysine, hydroxylysine and tryptophan. accumulation of glutaric acid brain damage