Flashcards in Biochemistry Deck (293)
CAG trinucleotide repeats; gene on chromosome 4
-depression, dementia, choreiform mvmnts, caudate atrophy, decreased GABA and decreased ACh
-symptoms between 20-50 yo
Fibrillin gene mutation
-connective tissue disorder affecting skeleton, heart, eyes
-tall, long extremities, pectus excavatum, hyperextensive joints, arachnodactyly
-cystic medial necrosis of aorta --> aortic incompetence, dissecting aorta, berry aneurysms; floppy mitral valve
-subluxation of lenses
inheritance pattern of the MEN syndromes (multiple endocrine neoplasias)
-MEN 2A and 2B are associated with ret gene
cafe au lait spots, neural tumors, Lisch nodules (pigmented iris hamartomas), skeletal disorders (ie scoliosis), optic pathway gliomas
Neurofibromatosis type 1 = von Recklinghausen's disease
-on chrom 17
Bilateral acoustic schwannomas, juvenile cataracts
-what disorder is this?
-what's its mode of inheritance?
-what gene is mutated and on what chromosome?
Neurofibromatosis type 2
-NF2 gene on chromosome 22
-mode of inheritance?
-incomplete penetrance and variable presentation
-Findings: facial lesions (adenoma sebaceum), hypopigmented ash-leaf spots, coritcal and retinal hamartomas, seizures, MR, renal cysts, renal angiomyolipomas, cardiac rhabdomyomas, increased incidence of astrocytomas
ash leaf spots (hypopigmented lesions on skin) + cardiac rhabdomyomas (+other possible symptoms too...)
Deletion of VHL gene on chromosome 3
von Hippel-Lindau disease
-deletion of VHL gene = tumor suppressor gene; get constitutive expression of HIF (transcription factor) and activation of angiogenic growth factors
-hemangioblastomas of retina/cerebellum, medulla
-50% of pts develop multiple bilateral renal cell carcinomas and other cancers
List the X-linked recessive disorders
"Be Wise, Fool's GOLD Heeds Silly Hope"
-Ocular albinism (general albinism = aut recessive!)
-Duchenne's (and Becker's) muscular dystrophy
-Hemophilia A and B
...also, Fragile X....
meconium ileus in a newborn. think:
CFTR gene mutation; mode of inheritance? Function of gene normally?
-CFTR gene codes for transmembrane protein that puts Cl from cell into lumen of pancreatic ducts and into lumen of airways; Na follows Cl into lumen, and water follows Na. But, with CFTR defect (abnormal protein folding), decreased water into lumen --> thick mucus
-mucus plugs lungs, pancreas, liver..
most common lethal genetic disease of Caucasians?
recurrent pulmonary infections + malabsorption + caucasian child? Think:
Why are males with CF infertile?
bilateral absence of vas deferens
Treatment for CF pts?
-N-acetylcysteine (inhaled; loosens mucus plugs)
-antibiotics (even fluoroquinolone in kids)
-fat soluble vitamins: A, D, E, K
Longest known human gene?
Dystrophin gene (DMD) --> mutated in Duchenne's and Becker's muscular dystrophy
Defect affecting the methylation and expression of the FMR1 gene and trinucleotide repeat of CGG?
-2nd most common cause of genetic MR
-MR, enlarged testes, long face, large jaw, large everted ears, autism, mitral valve prolapse
What are the 4 trinucleotide repeat expansion diseases (and what's being repeated)?
"Tri Hunting for my Fried Eggs (X)"
1) Huntington's disease (CAG)
2) Myotonic dystrophy (CTG)
3) Friedrich's ataxia (GAA)
4) Fragile X (CGG)
--> all may show anticipation!
flat facies, epicanthal folds, excessive skin at nape of neck, gap between 1st 2 toes, duodenal atresia, congenital heart disease
What does may a 1st trimester ultasound of a fetus with trisomy 21 show?
increased nuchal translucency
increased inhibin A
normal inhibin A
Edward's syndrome (trisomy 18)
MR, rocker-bottom feet, small jaw, low-set ears, clenched hands, congenital heart disease
Edward's syndrome (trisomy 18)
Pregnancy quad screen results in Patau's syndrome (trisomy 13)
Normal alpha-fetoprotein, beta-hCG, estriol, inhibin A
MR, rocker-bottom feet, small eyes, cleft lip/palate, holoprosencephaly (single mid-line eye), polydactyly, congenital heart disease
Patau's syndrome (trisomy 13)
Which chromosomes are commonly involved in Robertsonian translocations?
13, 14, 15, 21, 22
MR, microcephaly, high-pitched crying, epicanthal folds, VSD (or other cardiac abnormalities)
Cri-du-chat syndrome (congenital microdeletion of short arm of chromosome 5)
distinctive "elfin" facies, MR, hypercalcemia (and sensitivity to vitamin D), well-developed verbal skills and very friendly with strangers, CV problems
William's syndrome (think of Will ferrel in "Elf")
-d/t congenital microdeletion of long arm of chromosome 7 (including elastin gene)
90% of pts with DiGeorge syndrome have a deletion where?