Genetics and Dermatology Flashcards
De novo mutations are important factors in child growth disorders what are they?
A genetic alteration that is present for the first time in one family member as a result of a variant (or mutation) in a germ cell (egg or sperm) of one of the parents, or a variant that arises in the fertilized egg itself during early embryogenesis.
Define penetrance? What has a high penetrance?
How likely you are to get the condition if you have the mutation. Mendelian disorders have high penetrance. Multifactorial disorders have low penetrance.
What is one of the most common genodermatoses?
Tuberous sclerosis
How does tuberous sclerosis often present?
May present as infantile seizures
Earliest cutaneous sign is ash-leaf macule
Periungual fibromas – around nails
Facial angiofibromas (‘adenoma sebaceum’)
Cortical tubers and/or calcification of falx cerebri – may cause seizures
Hamartomas (normal tissue that there is too much of) = angiomyolipomas - heart, lung kidneys
Bone cysts – seen on x-ray
Type of inheritance of tuberous sclerosis?
Autosomal dominant
What is epidermolysis bullosa?
Group of blistering disorders due to autosomal recessive inheritance. Skin could break away when you touch or in less severe you just get blisters more easily
Describe 4 ways in which mutations can cause disease?
Haploinsufficiency
only one copy of working - reduced protein production
Dominant negative
expression of abnormal protein interferes with normal protein
Gain of function
Mutant protein gains a new function, affecting cell processes
Complete loss of protein
Autosomal recessive - 2 faulty copies of gene produce no protein
Describe cafe au lait macules
Occur from birth onwards
1 or 2 found in 10-20% of normal people
>5 suggests genetic disease
What is neurofibromatosis
Tumours form on nerve tissue. Lots of soft neural tumours and cafe au lait spots
