aneuploidy

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aneuploidy

 [an″u-ploi´de]
the state of having chromosomes in a number that is not an exact multiple of the haploid number. adj., adj an´euploid.

an·eu·ploi·d·y

(an'yū-ploy'dē),
State of being aneuploid.

aneuploidy

/an·eu·ploi·dy/ (an″u-ploi´de) any deviation from an exact multiple of the haploid number of chromosomes, whether fewer or more.

aneuploidy

[an′yoo͡ploi′dē]
any variation in chromosome number that involves individual chromosomes rather than entire sets of chromosomes. There may be fewer chromosomes, as in Turner's syndrome (one X chromosome in females), or more chromosomes, as in Down syndrome (three copies of chromosome 21). Such individuals have various abnormal physiological and morphological traits. Compare euploidy. See also chromosomal aberration, monosomy, trisomy.

an·eu·ploi·d·y

(an'yū-ploy'dē)
State of being aneuploid.

aneuploidy

An abnormality in the number of CHROMOSOMES by loss or duplication. The number may be smaller or greater than the normal diploid constitution. The loss of a whole chromosome is lethal. A chromosome extra to one of the pairs is called TRISOMY. Trisomy 21, for instance, causes DOWN'S SYNDROME. DNA aneuploidy refers to abnormal quantities of DNA in a nucleus. See also MOSAICISM.

aneuploidy

a condition where more or less than a complete set of chromosomes is found in each cell of an individual. Compare EUPLOIDY. Typically aneuploids have one extra or one missing chromosome. For example, in DOWN'S SYNDROME affected individuals have three number-21 chromosomes rather than the normal two, a condition known as TRISOMY. see CHROMOSOMAL MUTATION.

chromosome 

One of the thread-like structures located within the cell nucleus composed of an extremely long, double-stranded DNA (deoxyribonucleic acid) helix tightly folded around proteins called histones. Each chromosome carries genes that contain the hereditary material that controls the growth and characteristics of the body. There are 46 chromosomes in each human somatic cell organized in 23 pairs, of which 22 pairs are similar in appearance but differ at the molecular level. They are called autosomal chromosomes or autosomes and are designated by a number (with chromosome 1 being the longest, followed by chromosome 2, etc.). The other pair, the sex chromosomes determines the sex of the individual. In mammals the two sex chromosomes of females are alike (homologous) and are referred to as X chromosomes. Males carry one X chromosome along with a much shorter chromosome, the Y chromosome. Each chromosome has a centromere that divides it into two arms, the short arm 'p' and the long arm 'q'. Disorders of chromosome number in which the number of chromosomes is above or below the normal (46) are called aneuploidy. Common forms of aneuploidy are trisomy in which there is one extra chromosome and monosomy in which there is one less, than the normal 46. They rarely cause specific eye diseases but affected individuals present ocular manifestations. Examples: Down's syndrome (trisomy of chromosome 21), Edwards' syndrome (trisomy 18), Turner's syndrome (monosomy 45 XO). There are other chromosome abnormalities such as translocation (one segment of a chromosome is transferred to another chromosome) as may occur in congenital anterior polar cataract, deletion (a loss of a piece of chromosome) as in aniridia, choroideremia, retinoblastoma, etc. Other cases involve damage of a chromosome (e.g. fragile X syndrome). See defective colour vision; gene; mitosis; mutation.

aneuploidy

the state of having chromosomes in a number that is not an exact multiple of the haploid number; seen in karyotypes which have a small number of extra chromosomes or have a small number less than normal.
References in periodicals archive ?
The observed reduction of classification gap in z scores could be specific to paralog-based efforts or may more broadly reflect the difficulties of employing a limited number of data points (sequencing reads) and constrained target space (vs genome-wide) when detecting fetal aneuploidies from cfDNA.
Also, the pregnancy outcomes were not known in a small proportion of patients, but it is unlikely that aneuploidies would not have been reported if missed.
Maternal mosaicism is a significant contributor to discordant sex chromosomal aneuploidies associated with noninvasive prenatal testing.
sup][12] This finding indicates that most aneuploidies of fetal miscarriage spontaneously occur during the first trimester.
Clinical application of multiplex quantitative fluorescent polymerase chain reaction (QF-PCR) for the rapid prenatal detection of common chromosome aneuploidies.
The collaboration consolidates and streamlines delivery of prenatal testing options due to the combination of PerkinElmer's extensive prenatal testing menu with Verinata's proprietary technologies for the early, non-invasive identification of specific fetal chromosomal aneuploidies.
The presence of such high amounts of maternal DNA in maternal circulation in relation to the limited amount of fetal DNA poses a major challenge for the quantification of fetal DNA and the detection of fetal aneuploidies.
Some other aneuploidies (conditions where an abnormal chromosome number is present) are also common targets for prenatal detection, including trisomy for chromosomes 18 and 13 or abnormal numbers of sex chromosomes.
Cell-free DNA screening, or so-called noninvasive prenatal testing (NIPT), has had greatly increased utilization recently as advances in technology have elevated it almost to the level of a diagnostic test for detection of certain aneuploidies.
Aneuploidies become less prevalent as pregnancy progresses (30% in the second trimester), because most abnormal fetuses have miscarried earlier.
The test enables risk assessment for numerous foetal chromosomal aneuploidies or abnormalities in chromosomes, and also provides testing options for a number of additional common sex-related aneuploidies.
Identifying high-risk women for aneuploidies based on maternal age alone has a poor detection rate.