Genetics Flashcards
Disorders of chromosome no.
Down, Edward Patau Kleinfelter Turner
Most common autosomal trisomy
trisomy 21 or Down Syndrome
Antenatal signs of Down Syndrome
Nuchal thickening, flattened nose bridge
Clinical signs of trisomy 21
Simian crease, Wide sandal gap, Flat occiput, incurved fifth finger
Types of down syndrome
nondisjunction, mosaicism and translocation
What is the most common of the cytogenetics assoc with down syndrome?
non disjunction where chromosome 21 pair fails to separate at meiosis, therefore one gamete has two C21 and the other has none therefore fertilization of the gamete that has two C21 chromosomes results in Trisomy 21
What antenatal testing is done to detect trisomy 21?
FISH or rapid PCR testing. cell free dna is becoming part of routine testing
The risk of having another child is three times more likely than the normal risk if you hada previous Down syndrome baby
True normally it is 1 in 650 but it would beome 1 in 200
Robertsonian translocation is a part of what syndrome?
trisomy 21 and involves chromosomes 14 and 21
Clinical signs of Edward syndrome
overlapping fingers and rockerbottom feet
Patau Syndrome
Cleft lip and palate structural defect of brain
Doudenal atresian and congenital heart disease are imediate complications of what trisomy?
21
What are the clinical features of Turners 45 XO
lymphedema in neonates, short stature, webbed neck, ovarian dysgenesis, infertility, hypothyroidism, Coarction of the Aorta wide spaced nipples, renal anomalies recurrent otitis media
9 yo boy, tall stature, small testes and gynaecomastia. What is the diagnosis?
Kleinfelter’s 47 xxy
Cri du chat, di george and william syndrome are examples of what type of mutation?
deletions
Charcot Marie tooth is what kind of genetic abnormality
defect in myelination, autosomal dom, mutation in pmp22 duplication. dysfunction in peripheral nervous system affecting hands and foot especially peroneal and tibial nerves pes cavus pes planus and hammer toe foot drop inverted champagne bottle appearance
A 6-year-old boy is brought to your practice by his paternal grandmother for his first visit. She has recently received custody of him after his
mother entered the penal system in another state; she does not have much information about him. You note that the child is short for his age,
has downslanting palpebral fissures, ptosis, low-set and malformed ears, a broad and webbed neck, shield chest, and cryptorchidism. You hear a
systolic ejection murmur in the pulmonic region. His grandmother reports that he does well in regular classes, but has been diagnosed with
learning disabilities and receives speech therapy for language delay. His constellation of symptoms is suggestive of
noonan syndrome
