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Category Archives: Syndrome
Maternal age and syndromes
Maternal age and syndromes
What role does maternal age play on inheritance patterns?
- affects only the inheritance pattern of non-dysjunction. (ie. maternal age has no effect on mosaism or translocation)
Posted in Syndrome
Tagged , Inheritance pattern, Maternal age, Non-dysjunction, Syndromes
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Klinefelter Syndrome
Klinefelter Syndrome
What is the genetic abnormality?
47 XXY (2 or more X + 1 or more Y)
What are the inheritance patterns?
-non-dysjunction
-mosaism
What are the clinical features?
- decreased sexual characteristics:
- gonadal dysgenesis (testes atrophied with spermatogenesis and male infertility)
- decreased pubic hair and beard, absent low voice
- gynecomastia
- small penis
- long legs
Posted in Syndrome
Tagged , Gynecomastia, Klinefelter syndrome, Mosaism, Non-dysjunction
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Turner Syndrome
Turner Syndrome
Genetic abnormality and mode of inheritance:
1. lack of X chromosome
2. defective X chromosome
3. mosaic
Clinical features:
- wide spaced nipples, broad chest
- webbed neck
- amenorrhea, streak ovaries
- infertility
- short stature
- low hairline
- coarctation of the aorta
- cubitus valgus
- pigmented nevi
- peripheral lymphadema at birth
Posted in Syndrome
Tagged , amenorrhea, infertility, Streak ovaries, Turner, Turner syndrome, webbed neck, wide spaced nipples
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Neurofibromatosis Summary
Neurofibromatosis Summary
NF1 → neurofibrillin
NF2→ merlin
NF1
- NF
- café au lait spots
- Lisch nodules
NF2
- NF
- multiple meningiomas
- bilateral acoustic schwannomas
Posted in Syndrome
Tagged , Neurofibromatosis, Neurofibromatosis summary, Neurofibromatosis type 1, Neurofibromatosis type 2
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Ehlers-Danlos
Ehlers-Danlos
Ehlers-Danlos Syndrome:
- AD/AR
- mutations to structural genes or genes of enzymes affecting post-translation modification of collagen mRNA
- collagen
- collagen IV
- rupture of intestine and vessels
- skin is hyper-extensible
- fragile skin
Posted in Syndrome
Tagged , Bowel rupture, Collagen IV, Collagen mutation, Ehlers-Danlos, Ehlers-Danlos syndrome, Fragile skin, Hyper-extensible skin, Vessel rupture
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Marfan Syndrome
Marfan Syndrome
- inherited defect in extracellular glycoprotein, fibrillin
- mutations to FBN1 or FBN2 (FBN1 is on 15q21)
Marfan syndrome pathology
- skeletal system: long tapering fingers and toes, frontal bossing, kyphosis, scoliosis, ectopia lentis (bilateral subluxation or dislocation), pectus excavatum/pigeon chest
- CVS: MVP, cystic medionecrosis of the aorta-this can lead to:
-intramural hematoma – which can lead to aortic dissection-can lead to death
-dilation of aortic root (aneurysm) which leads to aortic incompentence → CHF
Marfan Syndrome Summary:
- autosomal dominant
- mutations in fibrillin 1/2, FBN
- long fingers, toes, legs
- pectus excavatum
- ectopia lentis
- cystic medionecrosis
- aortic insufficiency
- aortic dissection
- mitral valve prolapse MVP
- congestive heart failure CHF
Posted in Syndrome
Tagged , Aortic dissection, Aortic insufficiency, Congestive heart failure, Cystic medionecrosis, Ectopia lentis, FBN, FBN1, FBN2, Fibrillin, Glycoprotein fibrillin, Long fingers, Marfan, marfan syndrome, Mitral valve prolapse, Pectus excavatum
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Gardner syndrome
Gardner syndrome
- Osteomas (of mandible, skull and long bones)
- Exostoses
- Dental abnormalities (supernumerary teeth, mandible cysts, impacted teeth, unerupted teeth)
- Epidermoid cysts
- Fibromatosis
- Higher frequency of duodenal and thyroid cancer
Posted in Syndrome
Tagged , Duodenal cancer, epidermoid cyst, Exostosis, Fibromatosis, Gardner syndrome, Osteoma, thyroid cancer
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Turcot syndrome
Turcot syndrome
Tumors of the CNS
Two-thirds with APC gene mutations develop medulloblastomas
One-third with HNPCC gene mutations develop glioblastomas
Posted in Syndrome
Tagged , apc gene, Glioblastoma, HNPCC gene, medulloblastoma, turcot syndrome
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Sudden Infant Death Syndrome
Sudden Infant Death Syndrome SIDS
National child health definition for SIDS
1. Sudden, unexpected death in a child <1 year old that remains unexplained after a complete autopsy, a review of the clinical history and complete examination of the circumstances surrounding the death.
Risk factors in the child
1. Prematurity/low birth weight
2. History of previous SIDS in family
3. Male child
4. History of recent upper respiratory illness
5. Product of multiple birth
6. Brainstem abnormalities, defective arousal and cardiorespiratory control
7. ?GERD
Risk factors in the parent or child
1. Young mother (<20 years old)
2. Maternal smoking during pregnancy
3. Drug abuse
4. Short intergestational intervals
5. Low SES
6. Late or no prenatal care
Familial Adenomatous Polyposis Syndrome
Familial Adenomatous Polyposis (FAP) Syndrome
Familial Adenomatous Polyposis Syndrome Inheritance pattern
- autosomal dominant inheritance
- APC gene is on chromosome 5q21
- APC gene plays a role in the WNT pathway in the degradation of the beta-catenin
- beta-catenin role is to turn on transcription factors in the nucleus that lead to cell cycle progression
-mutations in the APC leads to absence of b-catenin degradation and signal independent tranlocation into the nucleus where it turns on the cell cycl
Familial Adenomatous Polyposis Syndrome Clinical Presentation
- two types of clinical presentations:
Classic Familial Adenomatous Polyposis
- minimum of 100 colonic polyps
- polyps in ampulla of Vater – this leads to a prophylactic colectomy in siblings and first-degree relatives which are at risk
Attenuated Familial Adenomatous Polyposis
- patients tend to develop fewer polyps (average 30), and most of the polyps are located in the proximal colon
- lifetime risk of cancer development is usually around 50%
Gardner syndrome
- polyps identical to those in classic FAP
- multiple osteomas (particularly of the mandible, skull, and long bones)
- epidermal cysts
- fibromatosis – desmoid tumors
- less frequent are abnormalities of dentition, such as unerupted and supernumerary teeth
- higher frequency of duodenal and thyroid cancer
Turcot syndrome
- combination of adenomatous colonic polyposis and tumors of the CNS
2/3 have have APC gene mutations and develop brain medulloblastomas
- 1/3 have mutations in one of the genes associated with HNPCC and develop brain glioblastomas
Gross Features of Familial Adenomatous Polyposis
-hundreds to thousands of adenomas evenly distributed through colorectum and appendix
- adenomas range from microscopic to 1cm in diameter with larger adenomas found in the rectosigmoid
- rectum occasionally spared, especially in the attenuated FAP
- colorectal carcinomas may be multifocal
Microscopic Features of Familial Adenomatous Polyposis
- histologically identical to sporadic adenomas
- normal intervening mucosa
- adenomas evolve from single adenomatous crypts
Symptoms and Management
- patients may be asymptomatic before puberty
- initial symptoms are rectal bleeding and diarrhea
- carcinomas start about 6 years after first symptoms
- 100% colon cancer without intervention
- treatment is prophylactic total colectomy
- following colectomy, the most common cause of death is periampullary cancer in 20%
Posted in Colon, GI, Syndrome
Tagged , adenoma, apc, apc gene, b-catenin, Cancer, carcinoma, Colon, colorectal, Familial Adenomatous Polyposis, gardner, periampullary cancer, polyps, Syndrome, turcot
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