Chromosomal Aberrations Overview

A technique to detect large-scale genetic changes in chromosomes.

Cells arrested at metaphase/prometaphase of cell cycle for karyotyping.

Techniques like G-banding to visually differentiate chromosome regions.

A common chromosome banding technique using Giemsa stain.

A standardized way to describe chromosome number and structure.

Changes in the number of chromosomes (e.g., trisomy, monosomy).

Changes in the structure of chromosomes (e.g., translocation).

International Standard for Cytogenetic Nomenclature for describing chromosome variations

The normal number of chromosomes for a species. In humans, this is 46 chromosomes in somatic cells, and 23 chromosomes in gametes.

A condition with a chromosome number that is a multiple of the haploid set. For example, triploidy (3n) or tetraploidy (4n).

A condition where there are three copies of each chromosome (3n). Often caused by failure of reduction division in meiosis.

A condition where there are four copies of each chromosome (4n). Usually caused by failure of the first zygotic division.

An abnormal chromosome number due to an extra or missing chromosome, but not involving the whole chromosome set.

Failure of homologous chromosomes to separate in meiosis I or sister chromatids in meiosis II or mitosis. This can lead to aneuploidy.

Failure of a chromosome or chromatid to be incorporated into a daughter nucleus during cell division due to delayed movement.

A karyotype where the total amount of genetic material remains normal, even though there is a structural rearrangement of chromosomes.

A karyotype where there is a gain or loss of genetic material due to a structural rearrangement.

The observable characteristics of an organism, which are a result of both genetic and environmental factors.

Having three copies of a chromosome instead of two in a diploid cell (2n+1).

Having only one copy of a chromosome instead of two in a diploid cell.

The karyotype for Down syndrome is (47, XY, +21) for males and (47, XX, +21) for females.

The karyotype for Turner syndrome is (45, X).

The presence of two or more genetically different cell lineages within one individual.

Mixoploidy arising from the same zygote resulting in different cell lineages.

Mixoploidy resulting from fusion of two different twin zygotes.

Down syndrome caused by nondisjunction during mitotic division, resulting in a mix of cells with different chromosome numbers.

Individuals formed by the fusion of two zygotes fertilized by two different sperm.

A condition in dispermic chimeras where an individual has both ovarian and testicular tissue.

Changes in the structure of chromosomes, often caused by breakage and reunion in different configurations. This can happen during crossing over (homologous chromosomes) or abnormally between non-homologous chromosomes.

A type of structural aberration where the chromosome complement is complete, meaning there's no loss or gain of genetic material. This is usually harmless, unless a critical gene is damaged during the rearrangement.

A type of structural aberration where the chromosome complement has an incorrect amount of genetic material due to loss or gain. These are often serious and can have clinical effects.

A structural aberration where a part of a chromosome is lost. Losing more than 2% of the haploid genome is usually lethal.

A structural aberration where genetic material moves from one chromosome to another. This can be reciprocal (segments are exchanged) or non-reciprocal (one chromosome loses material with the other gaining).

A pattern of inheritance where a single copy of a mutated gene on the X chromosome is enough to cause the disorder in both males and females. Females are often less severely affected due to X chromosome inactivation.

An affected father will transmit the trait to all of his daughters, but none of his sons, as he only passes on his Y chromosome to his sons.

An affected mother has a 50% chance of passing the trait to both her sons and daughters, regardless of their sex.

A disorder that affects bone growth and mineral metabolism, caused by mutations in the PHEX gene on the X chromosome. It leads to vitamin D-resistant rickets, affecting both males and females.

A pattern of inheritance where a gene on the Y chromosome is passed only from father to son, affecting only males.

Genes on the Y chromosome primarily control male sexual development and spermatogenesis.

A deletion or mutation in a Y-linked gene involved in spermatogenesis can lead to infertility in males, as it affects sperm production.

Used to detect genetic abnormalities like extra or missing chromosomes (aneuploidy), deletions, duplications, or rearrangements in chromosomes.

Karyotyping examines the number, size, and structure of chromosomes, looking for any deviations from the normal karyotype.

A genetic condition in females caused by the absence of one X chromosome, resulting in a 45, X karyotype.

A family tree diagram that illustrates the inheritance pattern of a specific trait over generations.

A trait or disorder where a single copy of the mutated gene is sufficient to cause the condition, affecting both males and females equally.

A diagram used to predict the probability of different genotypes and phenotypes in the offspring of a cross.

The pattern of a trait appearing in successive generations, with affected individuals having at least one affected parent.

A spontaneous change in a gene that can result in an inherited disorder in an individual without a family history of the condition.

A pattern of inheritance where a mutated gene on the X chromosome causes a disorder primarily in males. Females can be carriers but may not show symptoms.

A female who carries a mutated X-linked recessive gene but does not display the disorder. She can still pass the gene to her sons.

A severe X-linked recessive disorder affecting muscle development, leading to progressive weakness and often early death.

A tool used to predict the probability of offspring inheriting an X-linked recessive disorder. Shows the possible combinations of X and Y chromosomes.

The characteristic transmission of an X-linked recessive disorder through females, where affected males have affected maternal relatives.