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Flashcards in Biochem - genetics Deck (9):

Cafe au lait spots, polyostotic fibrous dysplasia, precocious puberty

McCune Albright

mutation affecting G-protein signaling, example of mosaicism


Locus vs allelic heterogeneity

locus - mutations at different loci = similar phenotype (eg. albinism)

allelic - different mutations in same locus = same phenotype (eg. B-thalassemia)


Hyperphagia, obesity, intellectual disability, hypogonadism, hypotonia

Prader-Willi (paternal gene deleted + maternal imprinting/silenced through methylation)

25% of cases due to maternal uniparental disomy


Inappropriate laughter, seizures, ataxia, severe intellectual disability

Angelman (paternal imprinting + maternal gene mutated)


Most common mutation of CFTR

F508 (phenylalanine)

Causes misfolded protein, which is then retained in RER and not transported to cell membrane, causes decr. Cl secretion


Reproduction in CF

males - absent vas deferens
females - amenorrhea, abnormally thick cervical mucus


Muscular dystrophy genetic mutations

Duchenne: frameshift --> truncated dystrophin protein

Becker: non-frameshift mutation --> partially function dystrophin protein

Dystrophin = anchor muscle fibers, connects actin cytoskeleton to transmembrane proteins which connect to ECM (loss results in myonecrosis)


Four Trinucleotide repeat expansion diseases

Fragile X syndrome (CGG)
Friedrich ataxia (GAA)
Huntington disease (CAG)
Myotonic dystrophy (CTG)

Show genetic anticipation (incr. severity, decr. age of onset)


Autosomal trisomies

Down: 21 (Drinking age)

Edwards: 18 (Election age), low-set ears! death w/in 1 yr

Patau: 13 (Puberty) cleft lip, polydactyly, holoprosencephaly, death w/in 1 yr