Autosomal Trisomies Flashcards
Events during prophase I of meiosis
- Pairing of homologous chromosomes (alignment and synapsis)
- Recombination between maternal and paternal chromosomes (meiotic cross-over/chiasmata)
- Segregation of homologous chromosomes
REDUCTION DIVISION
Spermatogenesis occurs _____ while primary oocytes are formed during _____
Spermatogenesis occurs THROUGHOUT POST-PUBERTAL LIFE while primary oocytes are formed during FETAL DEVELOPMENT (THE ARRESTED IN PROPHASE I UNTIL PUBERTY AND THEN YOU HAVE 2NDARY OOCYTE)
Nondisjunction in Meiosis I results in:
2 gametes with extra chromatid, and chromatid-less gametes
Nondisjunction in Meiosis II results in:
2 gametes with 1 chromatid, 1 gamete with 2 chromatids, and 1 gamete with no chromatids.
Ways to identify nondisjunction events
Via STR, RFLP, and VNTR analysis
Chosen marker should be close to centromere to avoid confounders since recombination usually occurs at the ends of the chromosomal arms.
Uniparental disomy can be caused by ______.
Recessive condition is observed in a patient with ____________.
Uniparental disomy can be caused by MEIOTIC NONDISJUNCTION.
Recessive condition is observed in a patient with ONLY ONE DOCUMENTED CARRIER PARENT.
Robertsonian translocation occurs between chromosomes ___ and ____
Robertsonian translocation occurs between chromosomes 14 and 21
Down Syndrome can occur via ____, ____, or ____.
Symptoms are: \_\_\_\_\_ \_\_\_\_\_\_ \_\_\_\_\_\_ \_\_\_\_\_\_ \_\_\_\_\_\_ \_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_ \_\_\_\_\_\_\_ \_\_\_\_\_\_ \_\_\_\_\_\_ \_\_\_\_\_\_
Down Syndrome can occur via MEIOTIC NONDISJUNCTION, ROBERTSONIAN TRANSLOCATION, or TRISOMY 21 MOSAICISM.
Symptoms are: Up-slanting palpebral fissures Epicanthal folds Flat nasal bridge Low set, small ears Protruding tongue Excessive skin on back of neck Brachycephaly Intellectual disability Early-onset AD Hypotonia AV septal defect Ventricular septal defect Duodenal atresia Annular pancreas Hirschprung's disease Transverse palmar crease Hyperflexibility Atlantoaxial instability Myeloproliferative disorder Acute megakaryoblastic leukemia Acute lymphoblastic leukemia Thyroid diease Diabetes
Edward syndrome is trisomy of chromosome __
-usually caused by ______, ____, or ____
Unique features: _____, ____, _____, _____, ____, _____, _____
Edward syndrome is trisomy of chromosome 18
-usually caused by NONDISJUNCTION, TRANSLOCATION, or TRISOMY 18 MOSAICISMS
Unique features: intrauterine growth retardation, prominent occiput, micrognathia, misshapen ears, clenched hands, rocker-bottom feet, omphalocoele, horseshoe kidney, patent ductus arteriosus
Patau syndrome is trisomy of chromosome ____
Often caused by: _____, _____, or _____
Unique features: ______, ______, ____, ______, _____, _____
Patau syndrome is trisomy of chromosome 13
Often caused by: MEIOTIC NONDISJUNCTION, UNBALANCED ROBERTSONIAN TRANSLOCATION (LONG ARM OF 13 TRANSLOCATED TO 14,21,22), or TRISOMY MOSAICISM
Unique features: anopthalmia, cleft lip, incomplete development of forebrain and optic/olfactory nerves, severe intellectual disability, polydactyly, omphalocoele, horseshoe kidney
Turner syndrome is ______ of _ chromosome
Usually caused by loss of ___ _ chromosome in either ____ or ____
Clinical features:
_____, _____, _____, ____, _____
Turner syndrome is MONOSOMY of X chromosome
Usually caused by loss of PATERNAL X chromosome in either MITOSIS or MEIOSIS
Clinical features:
Short stature, shield chest, webbed neck, aortic arch/valve problems, lymphedema, ovarian failure
Kleinfelter syndrome is a _____ of ___ chromosomes.
Most common cause is ____ in _____ chromosomes
Symptoms:
____, _____, ____, _____, ___, ____, _____
Kleinfelter syndrome is a TRISOMY of SEX chromosomes.
Most common cause is NONDISJUNCTION in PATERNAL chromosomes
Symptoms:
Long legs, difficult social interactions, infertility, decreased muscle tone, loss of libido, osteoporosis, gynecomastia
