Chap 10 Developmental Genetics and Abnormalities Flashcards

1
Q

What is aneuploidy and polyploidy?

A

Aneuploidy is the presence of abnormal number of chromosomes in a cell

Polyploidy is the state of a cell having more than two paired sets of chromosomes.

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2
Q

Explain Deletion in Chromosomes

A

Portions of chromosome are deleted and the effects depend on the region deleted, if a non essential part of the chromosome is deleted no harmful effects will occur. eg.17q12

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3
Q

Explain duplication in chromosomes and give an example.

A

Portion of the chromosome is duplicated. e.g Potocki Lupski Syndrome 17p11.2.Infants withPotocki-Lupski syndromemay have weak muscle tone (hypotonia) and swallowing difficulties (dysphagia) that lead to feeding problems.

Babies and children withPotocki-Lupski syndromehave delayed development, including delayed speech and language skills and gross motor skills such sitting, standing, and walking.

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4
Q

Explain inversion in chromosomes

A

Aninversioninvolves the breakage of a chromosome in two places; the resulting piece of DNA is reversed and re-inserted into the chromosome.

2 Types of Inversion

Paracentric inversion is inversion that occurs along the p or q arm and does not involve centromere

Pericentric inversion is inversion that involves the centromere

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5
Q

Explain translocation in chromosomes

A

A piece of a chromosome being attached to a non homologous chromosome.

Reciprocal Translocation where two detached fragments of non homologous chromosomes are switched.

Non Reciprocal Translocation where there is a transfer of segment if DNA from one chromosome to another non homologous chromosome.

Robertsonian Translocation is fusion of the whole long arms of two acrocentric homologous chromosomes.(acrocentric means small p arm)

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6
Q

Explain ring chromosomes and give an example.

A

Ring Chromosome is where the ends of a chromosome are fused together. eg. Ring Chromosome 14 Syndrome a condition characterized by seizures and intellectual disability.

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7
Q

Explain Isochromosome

A

Isochromosome is an abnormal chromsome that has two identical arms due to duplication of one arm and loss of the other.The chromosomes break on the transverse plane.

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8
Q

How do chromosomal abnormalities occur?

A

Non disjunction during M1 OR M2 (failure of the chromosomes to seperate)
During development of sperm and egg leads to meiotic disjunction trisomy or monosomy.

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