Question | Answer |
The presence of an extra copy of a genomic segment usually could result in a___ | partial trisomy |
The following regarding tandem duplications is true | direct duplication means the duplicate segment is in opposite direction as the original |
Partial monosomy typically causes more severe phenotype than partial trisomy of the same chromosomal region True or False | True |
Complementary microdeletion/microduplication syndromes does not include | Klinefelter syndrome |
Molecular studies could be used to detect ______ which is not detectable by FISH tests | the origin of duplication |
If a segment at the same position of both homologus chromosomes is drived from a single parent, it could also be called uniparental disomy for that segment True or False | True |
The following is NOT a mechanism of uniparental disomy? | DNA methylation |
Uniparental disomy (UPD) for 11p15 observed in Beckwith-Wiedemann syndrome (BWS) is an example of: | segmental paternal UPD. |
UPD could unmask a recessive gene and cause phenotypic changes that are not seen in heterozygous individuals True/False | True |
The cytogenetic abnormality seen in Beckwith-Wiedemann syndrome is | paternal duplication of 11p15.5. |
The following is NOT a feature of Beckwith-Wiedemann syndrome | Only paternal H19 tumor suppressor gene is expressed in normal individual |
Most of the chromosome 22 addition cases are due to unblanced gamete formation in balanced translocation carriers. True / False | False |
Uniparental disomy could exist in the form of | segmental/partial disomy, heterodisomy, isodisomy |
Uniparental disomy could be detected by G-band analysis. True / False | False |
The chance that trisomic rescue could result in a normal genotype is | 66% |
A big size of deletion occurs in heterochromatic region is usually unlikely to cause clinical changes True/False | True |
the following is NOT a function of telomerase? | Remove TTAGGG repeative sequence |
the following are functions of telomerase | Identify sites close to terminal chromosome deletion for binding, synthesize TTAGGG repeative sequence. |
About 5% of terminal deletions observed by karyotyping are actually interstitial by molecular methods. True / False | False |
Tiny interstitial deletions that might not be able to see under a light microscope include | microdeletion syndromes, contiguous gene syndromes, segmental aneusomy syndromes. |
Contiguous gene syndrome means the presence of clinical manifestation due to several genes in close proximity True/False | True |
Williams syndrome is an example of segmental aneusomy syndromes True/False | True |
The term "segmental aneusomy syndrome" is used to emphasize that the phenotype is the result of critical gene dosage imbalance within a genomic segment. True/False | True |
Most of the trisomilic syndroms are of _______ origin | maternal |
True or False?
The risk of autosomal aneuploidy increases when maternal age increases | True |
Meiosis II non-disjunction could happen when | sister chromatids malsegregated |
True or False?
Unbalanced structural rearrangements contain net loss or gain of genetic materials that is more likely to result in a clinically affected individual | True |
the following statement regarding the associated risk of a structural chromosome rearrangement is true | Risk for having another child with the same structural abnormality will be low if the abnormality found in first child is de novo |
A chilid had an apparently balanced de novo translocation demostrated severe mental retardation and developmental delay. Which of the following could be the possible mechanisms? | the translocation is not truely balanced, translocation invloved in the regulatory region of a critical gene, a position effect. |
True or False?
Autosomal monosomies are usually non-survivable | True |
True or False?
Autosomal aneuploidy occurs more frequent in sperms than oocytes. | False |
True or False?
Polyploidy are usually rare but survivable | False |
Tetrasomy 12p is known as ________ syndrome | Pallister-Killian |
True or False?
All cases of tetrasomy 12p reported were mosaics with a mixture of genetically normall cells and i(12p)-positive cells | True |
The cytogenetic origins of supernumerary marker chromosomes are not always known at the beginning and may represent autosomal aneuploidy in a form of: | tetrasomy, biosatellited dicentric chromosome, ring chromosome |
Which of the following could be an indication of balanced structural chromosome rearrangement | infertility, mulitple miscarriages, child with congenital anomalies |
True or False?
Structurally abnormal chromosomes could cause problem when pairing up with their homologous chromosomes which will result in unbalanced conceptions and eventually lead to miscarriage or spontaneous abortion. | True |
How does the imbalance rearrangement affect the severity of phenotype? | Imbalanced rearrangements involved chromosome 13, 18, 21, sex chromosomes could end up with live birth |
True or False?
Unbalanced conception could be lethal and lost without notice for an infertile woman | True |