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Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution.It can be defined as any duplication of a region of DNA that contains a gene.
In genetics, a maternal effect occurs when the phenotype of an organism is determined by the genotype of its mother. [1] For example, if a mutation is maternal effect recessive, then a female homozygous for the mutation may appear phenotypically normal, however her offspring will show the mutant phenotype, even if they are heterozygous for the mutation.
It shows 22 homologous autosomal chromosome pairs, both the female (XX) and male (XY) versions of the two sex chromosomes, as well as the mitochondrial genome (at bottom left). In genetics , a chromosomal rearrangement is a mutation that is a type of chromosome abnormality involving a change in the structure of the native chromosome . [ 1 ]
CAH can occur in various forms. The clinical presentation of each form is different and depends to a large extent on the kind of the underlying 21-hydroxylase enzyme defect. [9] Classical forms appear in infancy, and nonclassical forms appear in late childhood. The presentation in patients with classical CAH can be further subdivided into two ...
Uniparental disomy (UPD) occurs when a person receives two copies of a chromosome, or of part of a chromosome, from one parent and no copy from the other. [1] UPD can be the result of heterodisomy, in which a pair of non-identical chromosomes are inherited from one parent (an earlier stage meiosis I error) or isodisomy , in which a single ...
An example of a birth defect is cleft palate, which occurs during the fourth through seventh weeks of gestation. [14] Body tissue and special cells from each side of the head grow toward the center of the face. They join to make the face. [14] A cleft means a split or separation; the "roof" of the mouth is called the palate. [15]
A karyotype of an individual with trisomy 21, showing three copies of chromosome 21.. An abnormal number of chromosomes is known as aneuploidy, and occurs when an individual is either missing a chromosome from a pair (resulting in monosomy) or has more than two chromosomes of a pair (trisomy, tetrasomy, etc.).
The absence of the steroid hormones commonly associated with males drives Müllerian duct development and promotes the development of female genitalia, if anti-Müllerian hormone is suppressed or the body is insensitive, persistent Müllerian duct syndrome occurs when the individual has partial female reproductive, and partial male reproductive ...