Genetic instructions in the human body are packaged into structures called chromosomes, which are tightly coiled strands of DNA. Each human cell contains 23 pairs of chromosomes, with one set inherited from each parent, carrying the genes that guide our growth, development, and bodily functions. This article explores chromosome 10, detailing its role and the potential health implications when it is altered.
The Genetic Landscape of Chromosome 10
Chromosome 10 is an intermediate-sized human autosome, meaning it is not a sex chromosome. It is classified as submetacentric, a structure where the centromere is off-center, creating one long arm and one shorter arm. Composed of approximately 133 to 134 million DNA base pairs, it accounts for between 4% and 4.5% of the total DNA in a human cell.
Within its DNA, chromosome 10 is estimated to contain between 700 and 800 protein-coding genes. These genes provide the necessary instructions for creating proteins, which perform a vast array of tasks throughout the body.
One well-understood gene on chromosome 10 is the Fibroblast Growth Factor Receptor 2 (FGFR2) gene. It provides instructions for a protein involved in cell signaling, which helps direct cell division, maturation, and growth. The FGFR2 protein is particularly active during embryonic development in the formation of bones and other tissues.
Another gene on this chromosome is the RET gene, which provides instructions for producing a receptor tyrosine kinase protein. This protein is a component of cellular signaling pathways and is involved in the normal development of the nervous system and kidneys. Its functions include guiding the development of enteric neurons that govern intestinal function.
Types of Chromosomal 10 Abnormalities
Chromosomal abnormalities can be categorized as either numerical or structural. Numerical abnormalities involve a change in the total number of chromosomes, such as having an extra copy (Trisomy 10). Complete Trisomy 10, where every cell has three copies instead of two, is not compatible with life and results in miscarriage.
Monosomy 10 is the absence of one copy of the chromosome. Like complete trisomy, complete monosomy is lethal early in development. A variation is mosaicism, where the abnormality affects only a subset of the body’s cells. This condition can lead to a wide spectrum of outcomes depending on which cells and how many are affected.
Structural abnormalities alter a chromosome’s internal composition without changing the total number. A deletion occurs when a segment of the chromosome breaks off and is lost, such as a 10q deletion on the long arm (“q”). A duplication happens when a portion of the chromosome is incorrectly copied, like a 10p duplication on the short arm (“p”).
A rarer structural change is a ring chromosome, which forms when a chromosome breaks at the ends of both its short (p) and long (q) arms. The broken ends then fuse into a circular structure. This process often involves the loss of genetic material from the tips of the arms, disrupting the function of the affected genes.
Health Conditions Linked to Chromosome 10
Alterations to chromosome 10 are associated with several health conditions, from developmental disorders to an increased risk for certain cancers. The effects depend on the specific genes involved and the nature of the chromosomal change.
Distal 10q26 Deletion Syndrome results from the loss of a piece of the long (q) arm of chromosome 10. Individuals with this syndrome may exhibit developmental delays, mild to moderate intellectual disability, and characteristic facial features. Other features can include growth problems or abnormalities of the heart or genitals.
Chromosome 10p Duplication Syndrome is caused by an extra copy of a segment of the short (p) arm. Common features include intellectual disability and various physical anomalies. For both deletion and duplication syndromes, the specific symptoms and their severity depend on the size and location of the affected chromosomal segment.
Mutations in a single gene on chromosome 10 can also cause health conditions. For example, Apert syndrome results from specific mutations in the FGFR2 gene. This disorder is characterized by craniosynostosis, the premature fusion of skull bones, and syndactyly, the fusion of fingers and toes.
Mutations in the RET gene cause Multiple Endocrine Neoplasia Type 2 (MEN2). This is an inherited disorder that increases the risk of developing tumors in the glands of the endocrine system. These mutations create an overactive protein, triggering uncontrolled cell growth in the thyroid, adrenal, and parathyroid glands.