Genetics (week 5): Inheritance: Autosomal Dominant
congenital = present at birth
hereditary = inherited
familial = runs in family
genetic = caused by gene
reduced penetrance often at work in dominant diseases: genotype does not "penetrate" to phenotype
OSTEOGENESIS IMPERFECTA
OMIM 166200
autosomal dominant
collagen dz of type I collagen, COL1A gene (for pro-alpha collatgen) at 17q21.3
1/20,000
prog: fair, not curable but is txable
subtype I most common and mildest, type II very severe (lethal), at least 6 exist
sx: brittle bones, opalescent teeth, hearing deficit, short stature, malformed bones, lose joints
femur breaks from not much
Ivar the Boneless (most famous) in Scandinavian military, mastermind, 9th century
NEUROFIBROMATOSIS
OMIM 162200
aka Von Recklinghausen Dz
autosomal dominant
neurofibromin gene 17q11.3 (is GTP-ase regulator and negative regulator of "ras" gene)
tumor(s) grow along nerves
sx: **multiple neurofibromas
sx: cafe au lait spots, scoliosis, deformed, enlarged bones, learning disabilities, optic gliomas are common
**sig number of cases dt new mutations 30-50%
1/3000 for NF1 form
pedigree: vertical look downstream from new mutation (Nn)
odds for offspring are 50 50 plus new mutation chance
ACHONDROPLASIA
OMIM 100800
non-proportional dwarfism
autosomal dominant bone growth disorder
disproportionate growth of child: valgus/varus knees, long torso, adult heig under 4 feet, spinal kyphosis/lordosis, mb serious probs dt foramen magnum stenosis
mutation of fibroblast growth receptor gene 3 at 4p16.3
homozygous dominant genotype is lethal
gene product is negative regulator of bone growth
**new mutations account for ~75% of all cases
1/15,000-40,000
prog: OK, growth hormone tx experimental at this time
support group: Little People of America, very good group
actor Billy Barty had it, died a few years ago
MARPHAN SYNDROME
OMIM 154700
CT disorder
sx: tall w/ long limbs/arachnodactyly, subluxation of eye lens, pectus excavatum, dilation of arota v common
sx, mitral valve prolapse
fibrillin gene at 15q15-q21.1
1/5000 but new mutation rate about 1/20,000
prog: fair, tx for cv extends live, meds slow aortic dilation
POLYCYSTIC KIDNEY DZ
OMIM 173900
ADPKD is later onset condition
gene PKD1 at 16P13
autosomal dominant progressive disorder of kidnesy
mc cause of inherited renal failure
PKD sx: end stage kidney dz by age 60 or so
associated with aortic dilation
common: 1/500
15000 million people have it worldwide?!
FAMILIAL HYPERTROPHIC CARDIOMYOPATHY
VOL WILLEBRAND'S DZ
OMIM 193400
blood coage disorder, v common 1/100!
ACUTE INTERMITTENT PORPHYRIA
OMIM 176000
hepatic disorder or porphyrin metab
acute neuro-visceral attacks, urine turns red
EHLERS DANLOS SYNDROME
OMIM 130000
rare CT disorder, joint laxity, dermal hyperelasticity/fragililty
most autosomal dominant, some autosomal recessive and x linked
mild form type III also described
type V mb people who are just hypermobile
FAMILIAL ALZHEIMER'S DZ
OMIM 104300
mb sev dzs w/ same sx
progressive neronal loss, amyloid plaque and neurofibrillar tangles in cortex
familial is cleanly autosomal dominant: early onset
FAMILIAL POLYPOSIS OF THE COLON
OMIM 175100
tumor suppressor gene at 5q21 defective allowing formation of polyps which may-->malignant
DOMINANT OTOSCLEROSIS
OMIM 166800
hearling loss with reduced and variable penetrance
ossicles fuse, onset 10-30 years
5 genes implicated so far, multifactorial
common: 1/300
many more conditions see p59 of text
more than half of known genetic diseases are autosomal dominant
hereditary = inherited
familial = runs in family
genetic = caused by gene
reduced penetrance often at work in dominant diseases: genotype does not "penetrate" to phenotype
OSTEOGENESIS IMPERFECTA
OMIM 166200
autosomal dominant
collagen dz of type I collagen, COL1A gene (for pro-alpha collatgen) at 17q21.3
1/20,000
prog: fair, not curable but is txable
subtype I most common and mildest, type II very severe (lethal), at least 6 exist
sx: brittle bones, opalescent teeth, hearing deficit, short stature, malformed bones, lose joints
femur breaks from not much
Ivar the Boneless (most famous) in Scandinavian military, mastermind, 9th century
NEUROFIBROMATOSIS
OMIM 162200
aka Von Recklinghausen Dz
autosomal dominant
neurofibromin gene 17q11.3 (is GTP-ase regulator and negative regulator of "ras" gene)
tumor(s) grow along nerves
sx: **multiple neurofibromas
sx: cafe au lait spots, scoliosis, deformed, enlarged bones, learning disabilities, optic gliomas are common
**sig number of cases dt new mutations 30-50%
1/3000 for NF1 form
pedigree: vertical look downstream from new mutation (Nn)
odds for offspring are 50 50 plus new mutation chance
ACHONDROPLASIA
OMIM 100800
non-proportional dwarfism
autosomal dominant bone growth disorder
disproportionate growth of child: valgus/varus knees, long torso, adult heig under 4 feet, spinal kyphosis/lordosis, mb serious probs dt foramen magnum stenosis
mutation of fibroblast growth receptor gene 3 at 4p16.3
homozygous dominant genotype is lethal
gene product is negative regulator of bone growth
**new mutations account for ~75% of all cases
1/15,000-40,000
prog: OK, growth hormone tx experimental at this time
support group: Little People of America, very good group
actor Billy Barty had it, died a few years ago
MARPHAN SYNDROME
OMIM 154700
CT disorder
sx: tall w/ long limbs/arachnodactyly, subluxation of eye lens, pectus excavatum, dilation of arota v common
sx, mitral valve prolapse
fibrillin gene at 15q15-q21.1
1/5000 but new mutation rate about 1/20,000
prog: fair, tx for cv extends live, meds slow aortic dilation
POLYCYSTIC KIDNEY DZ
OMIM 173900
ADPKD is later onset condition
gene PKD1 at 16P13
autosomal dominant progressive disorder of kidnesy
mc cause of inherited renal failure
PKD sx: end stage kidney dz by age 60 or so
associated with aortic dilation
common: 1/500
15000 million people have it worldwide?!
FAMILIAL HYPERTROPHIC CARDIOMYOPATHY
VOL WILLEBRAND'S DZ
OMIM 193400
blood coage disorder, v common 1/100!
ACUTE INTERMITTENT PORPHYRIA
OMIM 176000
hepatic disorder or porphyrin metab
acute neuro-visceral attacks, urine turns red
EHLERS DANLOS SYNDROME
OMIM 130000
rare CT disorder, joint laxity, dermal hyperelasticity/fragililty
most autosomal dominant, some autosomal recessive and x linked
mild form type III also described
type V mb people who are just hypermobile
FAMILIAL ALZHEIMER'S DZ
OMIM 104300
mb sev dzs w/ same sx
progressive neronal loss, amyloid plaque and neurofibrillar tangles in cortex
familial is cleanly autosomal dominant: early onset
FAMILIAL POLYPOSIS OF THE COLON
OMIM 175100
tumor suppressor gene at 5q21 defective allowing formation of polyps which may-->malignant
DOMINANT OTOSCLEROSIS
OMIM 166800
hearling loss with reduced and variable penetrance
ossicles fuse, onset 10-30 years
5 genes implicated so far, multifactorial
common: 1/300
many more conditions see p59 of text
more than half of known genetic diseases are autosomal dominant