Introduction
1p deletion is a genetic disorder caused due to absent or missing genes from chromosome 1. This disorder is caused due to a genetic error called deletion. The other names for 1p deletion are chromosome 1p36 deletion, distal monosomy 1p36, and monosomy 1p36 syndrome. Gene deletion in chromosome 1 ranges from small to large deletions. 1p deletion genetic error is more frequently noted in females than males.
What Is Meant by Chromosomal Aberrations?
Chromosomal aberrations explain structural and numerical abnormalities. The chromosomal mutation is the other name for chromosomal aberration. Structural changes or abnormalities are called structural aberrations, and numerical changes or abnormalities are called ploidy changes or numerical aberrations. Structural aberrations comprise the errors in which a chromosome or gene segment is extra, lost, or located in another region (translocated). Chromosomal aberrations have been classified into four types, namely:
- Deficiency or deletion.
- Duplication.
- Inversion.
- Translocation.
What Is the Deletion Type of Chromosomal Aberration?
Deletion is a type of chromosomal aberration in which a segment of the chromosome and its genes are missing. Deletion is of the following four types namely:
- Terminal deletion.
- Intercalary deletion.
- Homozygous deletion.
- Heterozygous deletion.
When a gene or chromosomal fragment is deleted, there is just one break in the segment's terminal portion. The term "intercalary deletion" refers to a particular form of genetic mistake when a chromosomal segment or a set of genes are missing in the space in between. A deletion mistake of this type would result in two breaks in the section. In contrast to heterozygous deletion, which refers to the loss of chromosomal segments or genes from any homologous chromosomal pair, homozygous deletion defines the loss of chromosomes from the homologous chromosomal pair.
As previously mentioned, deletion is the kind of genetic mistake in which the loss of genetic material and the loss of genes are linked to negative consequences. For every genetic condition, this mistake manifests as a variety of indications and symptoms.
How Is 1p Deletion Caused?
1p deletion disorder is caused due to deletion of genetic material in chromosome 1 in the distal part of the short arm p. In most cases, the deletion of genetic material is noted in the terminal end of chromosome 1. More significant deletion shows more complex features than more minor deletion errors. Multiple genes are lost in this type of genetic error. At present, all genes are not studied. Researchers are working extensively on identifying the genes responsible for the disorder. Chromosomes are genetic constituents that are present in the nucleus of a cell. Every cell present in the body of an individual contains chromosomes. Chromosomes are responsible for distinct characteristics in every individual. Each chromosome has two arms, one short and the other long. The short arm is denoted as p, and the long arm is denoted by the letter q. The deletion of the genetic material generally occurs due to a spontaneous error and is mostly not inherited.
What Are the Clinical Features of the 1p Deletion Genetic Disorder?
The following are the most commonly reported general clinical features:
- Delayed growth.
- Altered development of speech.
- Motor skills such as sitting and standing are affected, which causes difficulty in carrying out daily activities.
- Attention deficit hyperactivity disorder is a commonly noted feature in 11q deletion. It is a neurodevelopmental disorder diagnosed in childhood and continues up to adulthood. Children suffering from this disorder have difficulty concentrating, get easily distracted, and have delayed thinking abilities; children suffering from this disorder have difficulty learning the alphabet, spelling, and mathematical tables.
- Compulsive behavior, such as shredding papers, is expected altered behavior in these children.
- As seen in autism, impaired socializing skills are also noted in these children.
- Few individuals also suffer from heart and kidney disorders.
The following are a few distinctive features reported in individuals suffering from 1p deletion:
- Trigonocephaly is a unique feature noted in infants with 1p deletion. The forehead of these individuals has a triangular shaped or keel shape. This is due to the altered fusion of brain sutures.
- The back of the head appears to be flat.
- Hypertelorism or widely spaced eyes are commonly noted.
- The Eyelid fold is slanted upwardly.
- Eyebrows have a high arch appearance.
- The midfacial region of the individual is generally flat in appearance.
- A short nose and flat nasal bridge are characteristic features in these individuals.
- Widened philtrum over the lips.
- Small lower jaw.
- Abnormally protruded lips.
- Ears are malformed.
- The palate has a high arch appearance.
The genetic disorders caused due to deletion errors, namely, 1p deletion, 6q deletion, 11q deletion, and 9p deletion, portray more or less similar characteristics, including delayed growth, retarded intellectual status, and distinctive facial appearance.
Is 1p Deletion Disorder Inherited?
1p deletion disorder is not an inherited disorder, and it is caused due to genetic error. This occurs due to a random error during the reproductive cell's production of eggs and sperm or early fetal development. Affected people have no history of a similar disorder but may pass this chromosomal deletion to their children. Five to ten percent of individuals even inherit these chromosomal deletion errors from parents unaffected by 1p deletion disorder. These chromosomal abnormalities produce symptoms that are typical of this genetic error.
What Are the Management Protocols for 1p Deletion Disorder?
Researchers are working to search for a definite treatment protocol for this disorder. The doctors focus on providing symptomatic relief that eases these individuals' daily activities. Psychiatrists aim to reduce the symptoms of behavioral disorders and improve these individuals' socializing skills. Physiotherapists seek to improve the motor skills of these individuals. So that they can sit, stand, and walk without any secondary support or minimum assistance. Dental practitioners aim to improve individuals' oral hygiene so that the caries rate is reduced. Specialized doctors treat individuals with severe signs and symptoms, including heart and kidney disorders, with utmost care.
Conclusion:
1p deletion disorder is a rare genetic disorder caused due to deletion of genetic material in chromosome 1's short arm p. The signs and symptoms vary widely; thus, clinicians should thoroughly examine the patients. Solid treatment and protocol are unavailable, but various research is going on in medical genetics to treat this disorder. Genetic mapping and targeted gene therapy are extensively studied for their application in diagnosing and treating rare genetic disorders like 1p deletion.
