Uniparental disomy of 5

Uniparental Disomy of Chromosome 5

Uniparental disomy (UPD) occurs when a person receives two copies of a chromosome, or part of a chromosome, from one parent and no copies from the other parent. This can lead to various genetic disorders depending on the chromosome involved. Uniparental disomy of chromosome 5 is a rare genetic condition that can have significant clinical implications.

Overview

Uniparental disomy of chromosome 5 can occur as either maternal UPD (both copies of chromosome 5 are inherited from the mother) or paternal UPD (both copies are inherited from the father). The effects of UPD can vary depending on whether the chromosome involved is subject to genomic imprinting, a process where certain genes are expressed in a parent-of-origin-specific manner.

Mechanism

UPD can arise through several mechanisms:

• Trisomy Rescue: This is the most common mechanism, where a trisomic embryo (with three copies of a chromosome) loses one copy to restore a normal disomic state. If the lost chromosome is from the parent who contributed only one copy, UPD results.
• Monosomy Rescue: A monosomic embryo (with one copy of a chromosome) duplicates its single chromosome to restore disomy, leading to UPD.
• Gamete Complementation: This occurs when a gamete with no copies of a chromosome is fertilized by a gamete with two copies.

Clinical Implications

The clinical consequences of UPD of chromosome 5 depend on whether any imprinted genes are located on this chromosome. Currently, chromosome 5 is not known to have any imprinted genes, so UPD of chromosome 5 may not have the same effects as UPD of chromosomes with known imprinted regions, such as chromosome 15. However, UPD can still lead to clinical issues if it unmasks a recessive genetic disorder. If there is a recessive mutation on chromosome 5, having two copies from one parent could result in the expression of this disorder.

Diagnosis

Diagnosis of UPD typically involves genetic testing, such as:

• Karyotyping: To identify any chromosomal abnormalities.
• Molecular Genetic Testing: Techniques such as SNP arrays or microsatellite analysis can be used to detect UPD by identifying regions of homozygosity or lack of heterozygosity.

Related Conditions

While UPD of chromosome 5 itself may not be associated with specific syndromes, it is important to consider the potential for recessive disorders or other chromosomal abnormalities that could be unmasked by UPD.

Research and Future Directions

Research into UPD continues to evolve, with ongoing studies aimed at understanding the full implications of UPD on human health and development. Advances in genomic technologies are likely to improve the detection and understanding of UPD and its effects.

See Also

• Uniparental disomy
• Genomic imprinting
• Chromosomal disorders

==

External Links

• [Genetics Home Reference - Uniparental Disomy](https://ghr.nlm.nih.gov/)
• [OMIM - Online Mendelian Inheritance in Man](https://www.omim.org/)

NIH genetic and rare disease info

• NIH info on Uniparental disomy of 5

Uniparental disomy of 5 is a rare disease.