GeneticsDiseasesExam1.txt

XR

XR

XR; mutation in Xq13 ---> deletion of helicase gene ATRX which is responsible for many gene expression ---> loss of expression of HbA(hemophilia) or mental retardation

XD; Female only- lethal in males; mutation in MECP2 protein involved in transcriptional silencing and regulating methylation; hand wringing, seizures, mental retardation, regression of skill and speech.

XD; defect in PHEX gene which is an endopeptidase involved in phosphate regualtion; *Vit.D resistant rickets, bone deformation, short stature

XD; *cellular interference makes it less severe in males; defect in EFNB1 gene for ephrin receptor so fail to establish tissue boundaries; mental retardation seizures.

ARD

ARD; *locus heterogeneity; PKE2 is more severe than PKE1

ADD; mutation in FBN1 which encodes connetive tissue protein fibrillin-1; tall, long limbs, thin fingers, heart valve deficit, joint problems, flat feet, high TGF-beta levels, manage by preventing dilation of aorta via beta-blockers, ACE inhibitors, lower HR and BP, see cardiologist

ARD; diagnose with high Cl- in sweat; mutation in CFTR channel causes loss of function of Cl- channel; lung via pseudomonas aeruginosa, GI, pancrease, hepatobiliary cirrosis

XR; Manesfesting heterozygote (ie lyonization) can occur; symmetrical muscular weakness, calf hypertrophy, symptom before age 5 means wheel chair dependent before 13 yrs

mitochondrial disease; hyperemia of optic disk with blurred margins, cloudy, loss of vision; reduced penetrance at 45%

ADD;Dom (-) activity; CAG nucleotide repeat (poly Glut); onset after 35-45 years; involuntary head movement, degenerating brain, 26-40 normal to full penetrant HD

ADD; may not see vertical pedegree cus 50% are new founder cases

ARD; mutation in HEXA gene causing accumulation of gangliosides in lysosome; high prevelence in ashkenazi jews; severe in acute infantile- progressive weakness, loss of motor skills, blindness, seizures, spacticity, death before age 4 or adult onset chronic- slower and bipolar psychosis

ADD; gain of function type; *no vertical pedegree; mutated FGFR3 growth factor receptor gene causes an overactive tyrosine kinase increases differentiation and stops growth

ADD; haploinsufficiency; mutated LDL receptor of binding domain of apolipoprotB-100; aortic valve stenosis, high cholesterol, corneal arcus, tenosynovitis, Xanthelosma palpebrarum, tuberous xanthamus; treat with statins

XR

Trisomy 21; most common 1/800 births; male sterile/female fertile; 66% due to nondisjunc in MI; mental retardation, heart malformation, high leukemia, GI tract, duodenal stenosis, imperforate anus, hirschsprung (enlarged colon)

45 X; loss of pseudoautosomal region; short stature, sexyal infantilism, heart defect, kidney defect, puffy feet, extra skin; 60-80% loss of Y during Meiosis or mosaic loss during mitosis

Trisomy 17; 1/6000 births, 95% Spontatenously aborted; 50% of born die within 1st week; 95% die within first year

Trisomy 13; 1/10K births, mental retard, motor deficiency, polydactyly, heart deficit, eye and cleft palate

47 XXY, one barr body inactivated so no pseudoautosomal region; hypogonad, taller, longer arm, sterility due to atrophy of seminiferous tubules, low testosterone, gynecomastia, low IQ, low muscle mass

some sterility menstrual irregularies, mild mental retard, due to nondisjunction

increased incidence in prison pop. 1/30 compared to 1/1000 normally; Can only occur with nondysjunction in MII; Taller, lower IQ, ADD and learning disability

cross over of X and Y chromosome occurs during meiosis but can occur outside of the pseudoautosomal region so SRY gene is swapped onto X chromo; sex determined at a 6 weeks; each has all plumbing of the other, no one has sperm or egg