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X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be always expressed in males (who are necessarily hemizygous for the gene mutation because they have one X and one Y chromosome) and in females who are homozygous for the gene mutation (see zygosity). Females with ...
The following is a list of genetic disorders and if known, type of mutation and for the chromosome involved. Although the parlance "disease-causing gene" is common, it is the occurrence of an abnormality in the parents that causes the impairment to develop within the child.
The incidence of X-linked recessive conditions in females is the square of that in males: for example, if 1 in 20 males in a human population are red–green color blind, then 1 in 400 females in the population are expected to be color-blind (1 / 20)*(1 / 20). Examples include: Aarskog–Scott syndrome; Adrenoleukodystrophy (ALD) Bruton's ...
Achondroplasia is a skeletal system disorder caused by a recessive allele that can still result in a live birth in the homozygous state. [8] One mutant allele for achondroplasia can be tolerated, but having two results in death. In the case of homozygous achondroplasia, death almost invariably occurs before birth or in the perinatal period.
Autosomal recessive disorders occur in individuals who have two copies of an allele for a particular recessive genetic mutation. [23] Except in certain rare circumstances, such as new mutations or uniparental disomy , both parents of an individual with such a disorder will be carriers of the gene.
An allele [1] (or allelomorph) is a variant of the sequence of nucleotides at a particular location, or locus, on a DNA molecule. [2]Alleles can differ at a single position through single nucleotide polymorphisms (SNP), [3] but they can also have insertions and deletions of up to several thousand base pairs.
X-linked recessive chondrodysplasia punctata; X-linked sideroblastic anemia and spinocerebellar ataxia; X-linked spinal muscular atrophy type 2; XMEN disease
According to the model of Mendelian inheritance, alleles may be dominant or recessive, one allele is inherited from each parent, and only those who inherit a recessive allele from each parent exhibit the recessive phenotype. Offspring with either one or two copies of the dominant allele will display the dominant phenotype.