DIT review - Reproduction 3 Flashcards
Most common #1 and #2 cause of genetic intellectual disability + most common cause overall
1 genetic cause = Trisomy 21
Most common cause overall = Fetal alcohol syndrome
Quad screen values in trisomy 21
- Decreased alpha-fetoprotein
- Increased b-hCG
- Decreased estriol
- Increased Inhibin A
Genetic causes of trisomy 21
- 95% due to meiotic nondisjunction
- 4% due to unbalanced Robertsonian translocation (between chromosome 14 and 21)
- 1% due to mosaicism
Presentation of Edwards Syndrome
Trisomy 18
- Prominent occiput
- Rocker-bottom feet
- Intellectual disability
- Clenched fists
- Low set ears
- Micrognathia (small jaw)
- Death usually by age 1
Quad screen values in trisomy 18
- Decreased alpha-fetoprotein
- Decreased b-hCG
- Decreased estriol
- Normal Inhibin A
Presentation of Patau syndrome
Trisomy 13
- Intellectual disability
- Rocker bottom feet
- Microphthalmia
- Microcephaly
- Cleft lip/palate
- Holoprosencephaly
- Death usually by age 1
Abnormal values of first trimester pregnancy screen in Trisomy 13
- Decreased b-hCG
- Decreases PAPP-A (pregnancy-associated plasma protein A)
- Increased nuchal translucency
Trinucleotide repeat and gene involved in Fragile X
- Trinucleotide repeat – CGG
- FMR1 gene (THINK: Fragile Mental Retardation)
Presentation of Fragile X
- Macroorchidism
- Long face
- Long everted ears
- Autism
- Mitral valve prolapse
- Intellectual disability
Chromosome abnormality and presentation of Klinefelter syndrome
- 47, XXY
- All male
- Testicular atrophy, eunuchiod body shape, tall, long extremities, gynecomastia, female hair distribution
- THINK: Charlie
- Presence of barr body (inactivated X chromosome)
- Dysgenesis of seminiferous tubules à decreased inhibin B à increased FSH
Chromosome abnormality and presentation of Turner syndrome (what is the cardiac abnormality?)
- 45, XO
- All female
- Short stature, broad (shield) chest, webbed neck, streak ovary (lack of paternal X chromosome causes loss of follicles within the ovary by age 2), bicuspid aortic valve, coarctation (femoral < brachial pulse), horshoe kidney
- Most common cause of primary amenorrhea
- Decreased estrogen will cause increased LH and FSH
Presentation of Double Y Males (XYY)
- 47, XYY
- Phenotypically normal
- Very tall, severe acne
- May have antisocial behaviors
Mutation and presentation of Cri-du-Chat syndrome
- Microdeletion of short arm of chromosome 5 (45, XX or 45, XY, 5p-)
- Microcephaly, intellectual disability, high pitched crying/mewing, cardiac abnormalities
- THINK: Cry of the Cat
Mutation and presentation of Williams syndrome
- Microdeletion of long arm of chromosome 7 (deletion includes elastin gene)
- “Elfin” facies, intellectual disability, hypercalcemia, well-developed verbal skills, extreme friendliess with strangers
- THINK: Will Ferrel in the movie elf
What is the defect in Li-Fraumeni syndrome
- Defective p53 (tumor suppressor) - multiple malignancies at an early age
What is the mutaiton in Neurofibromatosis type 1
- Caused by mutation in NF1 gene on chromosome 17
- This gene is responsible for control of cell division
Presentation of NF Type 1
- Neurocutaneous disorder characterized by café-au-lait spots, cutaneous neurofibromas, optic gliomas, pheochromocytomas, Lisch nodules (pigmented iris hamartomas)
What is the mutation of neurofibromatosis type 2
- Due to mutation of NF2 gene on chromosome 22
Presentation of Neurofibromatosis type 2
- Presentation:
- Hearing loss, tinnitus, balance problems, hyperpigmented skin lesions, cataracts
- REMEMBER 2’s:
- Chr 22
- Bilateral hearing loss
- NF Type 2
- Cataracts
Mutation in Autosomal Dominant Polycystic Kidney Disease (ADPCKD)
- Due to mutation in APKD1 on chromosome 16
Presentation of ADPCDK
- Numerous cysts in cortex and medulla causing bilateral enlarged kidneys
- Presentation:
- Flank pain, hematuria, HTN, UTI, progressive renal failure
- Also associated with Berry aneurysms, mitral valve, prolapse, and liver disease