Genetic disorders Flashcards
1
Q
- It’s characterized by vertical transmission
- Can see reduced penetrance (RP)
- You only need to inherit one defective allele to present w/ symptoms
- Homozygous dominants are often more severely affected than heterozygotes
- homozygous recessive individuals are healthy/ not affected and can’t pass on the disease.
A
Autosomal dominant (AD) inheritance pattern
2
Q
- Marfan syndrome (presents with ectopia lentis, arachnodactyly, heart problems)
- Neurofibromatosis (NF, presents w/ cafe au lait spots)
- Huntington’s Disease (HD, it’s a disease of anticipation that’s due to a CAG trinucleotide repeat expansion. CAG codes for Gln)
- Retinoblastoma
- Waardenburg syndrome
- Myotonic dystrophy (It’s a disease of anticipation that’s due to a CTG trinucleotide repeat expansion. It presents with frontal baldness and muscle wasting)
- Type IIA hyperlipidemia (familial hypercholesterolemia)
- Familial adenomatous polyposis (FAP)
- Hereditary spherocytosis (HS, due to defective ankyrin and spectrin)
- EHD4 (most severe form of EHD, it’s vascular)
- AIP (no photosensitivity, due to defective PBG deaminase)
- Achondroplasia
- OI (except OI type VII)
- Polydactyly
A
AD disorders
3
Q
- It’s characterized by horizontal transmission
- Need to inherit 2 defective alleles to present with symptoms
- Same number of men and women affected
- Often see consanguinity
- Heterozygotes are asymptomatic carriers
- Homozygous dominants are normal and not affected, and can’t transmit the defective allele
- Homozygous recessives are affected
A
Autosomal recessive (AR) inheritance pattern
4
Q
- Abetalipoproteinemia (No/low serum chylomicrons, LDL, and IDL. HDL level is not affected)
- Alkaptonuria (disorder or Phe/Tyr metabolism, urine turns black when air hits it)
- Bernard-Soulier syndrome (It’s due to defective GPIb receptor, GPIb is receptor for von Willebrand factor vWF, pts have problems with blood clottin)
- Bloom syndrome (presents as butterfly shaped rash, it’s due to defective DNA helicase)
- CAH
- CF
- Cystinosis/Cystinuria
- Fanconi anemia
- Gaucher’s disease (Crumpled paper inclusions, it’s due to defective glucocerebrosidase)
- Friedrich’s ataxia
- GSDs (Glycogen storage diseases)
- Hartnup disease
- Wilson’s disease (It’s due to defective ATP 7B, it’s Cu2+ toxicity, presents with fleischer (copper) rings around eyes)
- Werner syndrome
- Tay Sachs disease (Cherry red macula, GM2 accumulates, it’s due to defective hexosaminidase A)
- Xeroderma pigmentosum (it’s due to defective NER, can’t remove thymine-thymine dimers)
- Niemann-Pick disease (Cherry red macula, hepatosplenomegaly, sphingomyelin accumulates, it’s due to defective sphingomyelinase)
- Thalassemia
A
AR disorders
5
Q
- Affected fathers give it to all their daughters but to none of their sons
- Carrier mom gives to all her sons, but none of her daughters, affected sons do not pass it on to their sons, but can pass it on to their daughters.
A
XLR inheritance pattern
6
Q
- Color blindness
- Hemophilia
- Duchenne’s muscular dystrophy
- Gluc 6 PDH deficiency
- OTC deficiency
A
XLR disorders
7
Q
- Hypophosphatemic rickets
- Incontinentia pigmenti
A
XLD disorders
8
Q
- Mom gives it to all her kids
- Affected sons do not pass it on, but affected dughters pass it on to all of their children
A
Mt inheritance
9
Q
- Mt. encephalopathy w/ lactic acidosis and stroke like episodes (MELAS) (It’s due to defective oxidative phosphorylation (OXPHOS) MELAS pts have marked decrease in complex I activity)
- Myoclonic epilepsy w/ ragged red fibers (MERRF)
- Leigh syndrome
- Leber hereditary optic neuropathy (LHON)
- Neurogenic weakness w/ ataxia and retinitis pigmentosus (NARP)
A
mt disorders
