03/15g Genetic Mechanisms of Pathology II Flashcards
What is the most common genetic cause of mental retardation?
Trisomy 21/Down’s Syndrome
What is fragile X syndrome?
X-linked genetic disorder caused by an expansion of triplet repeats in the UTR of the FMR-1 gene
Expansion leads to decreased expression of the FMR-1 protein - causes mental retardation
Exhibits genetic anticipation
What are the symptoms of Ehlers-Danlos Syndrome?
Fragile, easily bruisable skin
‘Cigarette-paper’ scars
Joint hypermobility
What are the characteristics and symptoms of Marfan syndrome?
Increased height Long limbs and digits Mild joint laxity Vertebral column deformity Narrow, highly arched palate Valvular disease Major life-threatening complication - aortic aneurysm and dissection
What is the inheritance mechanism of Ehlers-Danlos syndrome?
Autosomal dominant
Due to mutations in collagen-alpha genes
What is the inheritance mechanism of Marfan syndrome?
Autosomal dominant
Due to mutations in fibrillin
When should you order a karyotype?
Prenatal diagnosis
Infertility or multiple miscarriages
Determination of carrier status for family planning
What three gross chromosome abnormalities are compatible with life?
Trisomy 21, 13, and 18
What other pathologies are associated with Down’s syndrome?
Congenital heart defects
Acute leukemias
Early Alzheimer’s disease
What is Klinefelter’s syndrome?
XXY karyotype
Characteristics - atrophic gonads, infertility, mild gynecomastia, little body hair
What is Turner syndrome?
45,X karyotype
Clinical characteristics - short stature, webbed neck, hypothyroidism, amenorrhea, hypogonadism
Often associated with congenital heart defects such as coarctation of the aorta and bicuspid aortic valve
What is DiGeorge syndrome?
Chromosomal deletion that leads to a failure of pharyngeal arch development
Clinical characteristics - parathyroid hypoplasia and hypocalcemia, thymic hypoplasia and T cell immunodeficiency, palate deformities, congenital heart defects, and mental retardation
