Chromosomal Microarray as a First-Line Diagnostic Test for Developmental Delay and Mental Retardation Cases

Chromosomal microarray is an effective genetic testing method for identifying copy number variations (CNVs) in a person's DNA. Chromosomal microarray (CMA) testing detects copy number variations (CNVs), often known as the addition or deletion of abnormal chromosomal areas.

It is one of the most effective, high-resolution, and whole-genome techniques to identify chromosomal abnormalities responsible for genetic illness and development problems. It helps in quantifying the number of copies of thousands of segments of DNA continuously. The chromosome microarray can identify small missing or extra deoxyribonucleic acid segments, also called copy number variants.

This article discusses how CMAs can be deployed as the first line of tests for individuals presenting developmental delay, intellectual disability, autism spectrum disorder, and multiple congenital anomalies.

Understanding Chromosomal Microarray Analysis

Chromosomal microarray analysis aids in detecting genetic material gains or losses that can be connected to certain genetic diseases or ailments. Compared to conventional karyotyping, this approach offers improved resolution and accuracy, enabling a more thorough examination of the genome. Clinical genetics frequently use it to identify hereditary diseases, developmental abnormalities, and intellectual disabilities.

CMA detects genomic gains and losses at a considerably better resolution than G-banded karyotyping. Furthermore, according to its genome-wide design, it enables the detection of new copy number changes. The existing literature indicates that the diagnostic yield of CMA, which ranges from 5-20%, is influenced by the microarray platform, patient selection, and interpretation criteria.

What Anomalies Can Chromosomal Microarrays Detect?

Here is the list of the congenital genetic disorders that chromosomal microarray analysis helps detect:

Chromosome segments can have numerous genes in microdeletions and microduplications, which are too tiny to capture under a microscope.
Trisomy, monosomy, and other chromosome number anomalies that most commonly occur, including Down syndrome.
Disproportionate chromosomal rearrangements such as translocations, etc.
Highly homozygous individuals who are at risk for inheriting a disease or developing imprinting abnormalities
Tetraploid is a condition in which all the chromosomes are duplicated.

Causes and Risk factors of developmental delay

Anytime during the growth stage, developmental problems can begin, and they typically last for the rest of a person's life. Most developmental problems start before birth, but some can occur afterward due to trauma, infection, or other circumstances. Many different causes are known to contribute to the majority of developmental disorders. Here are some reasons that can lead to developmental delay:

Maternal infections during pregnancy, such as cytomegalovirus (CMV) infection, problems after birth, and head trauma, can lead to hearing loss in infants.
Fetal alcohol syndrome problems, genetic and chromosomal disorders like Down Syndrome, and certain infections during pregnancy are some of the most typically recognized causes of intellectual disability.
Children who have a sibling with autism spectrum disorder are more likely to get the condition themselves.
Premature birth, multiple births, infections during pregnancy, and low birth weight are all linked to an elevated risk for various developmentalimpairments.
Untreated infant jaundice (high blood bilirubin levels in the first few days after birth) can result in kernicterus, a type of brain injury. Cerebral palsy, issues with hearing and vision, and dental issues are more prevalent in children with kernicterus. Kernicterus can be avoided by identifying and treating infant jaundice immediately.

Causes and Risk Factors of Mental Retardation

Complex elements may interact to generate the complex disease known as mental retardation or intellectual delay. Defects in the genes or chromosomes, injuries or disorders that form and worsen while a fetus is developing in the womb, diseases of early childhood, and environmental factors are all potential causes of mental retardation.

Here are some conditions causing intellectual delay are:

The most frequent cause of mental retardation is iodine deficiency, which can also induce hypothyroidism because it interferes with brain growth.
Mental retardation can be brought on by illnesses like HIV, meningitis, listeriosis, encephalitis, congenital toxoplasmosis, congenital rubella, and congenital CMV that are present at birth or develop later.
The mother's use of toxins like alcohol, cocaine, amphetamines, and other drugs during pregnancy is another potential culprit.
Several genetic diseases, such as Down syndrome
Consuming alcohol while pregnant
Psychosocial factors in the mother can also be reflected in the fetus.
Exposure of the mother to environmental pollutants

When to visit a doctor?

Children with developmental delays show a range of problems that might impair a child's physical, cognitive, communicative, social, emotional, and behavioral skills.

During infancy and early childhood, milestones such as rolling over, smiling, babbling, sitting up, crawling, and walking start appearing on a largely predictable timetable. For instance, a newborn should be able to lift their head and smile by three months. Most infants can roll over and grab tiny items by six months.

Pediatricians examine youngsters for key milestones during routine well-child visits and notify parents of any problems. Pediatricians may detect a developmental delay when a child has trouble completing these milestones, even though the attainment of these milestones varies. Some developmental delays, like speech, gross motor, and fine motor delays, may become evident in a baby or toddler's early years. For example, high-level cognitive, sensory processing, social, and emotional deficits could not be noticeable until a kid starts school.

Schedule an appointment with a doctor if a child exhibits any of the following symptoms:

Difficulty reading and writing
Social immaturity
Low IQ
Autism
Epilepsy
Physical disability
Slower language comprehension and use
Inability to live independently
Impaired motor skills
Seizures

Accompanied by other behavioral symptoms like aggression, dependence, withdrawal from activities, attention-seeking, depression, or you notice a change in their emotional state, social behavior, or physical abnormalities, it is advised that you get your child tested for intellectual disabilities.

Wrapping up,

Chromosomal Microarray Analysis is considered a first-line test for investigating non-syndromic development delay or intellectual delay. It offers a greater resolution than traditional karyotypes because it can detect smaller variations and provide a greater diagnostic yield.

Apollo Diagnostics can help you take medical tests at the convenience of your home. We assure the utmost care and safety while handling the tests and ensuring accurate results. Visit our website to book your test today! You can visit the Apollo Diagnostic Center for more expert assistance.

Frequently asked questions

1. What is a chromosomal microarray test?

Chromosomal microarray (CMA) testing detects copy number variations (CNVs), often known as the addition or deletion of abnormal chromosomal areas. It aids in the detection of genetic material gains or losses that can be connected to certain genetic diseases or ailments.

2. What is the meaning of mental retardation or intellectual disability?

Significant impairments in cognitive functioning and adaptive behavior, as shown by conceptual, social, and practical adaptive skills, are characteristics of intellectual disability. This condition first appears before the age of 18.

3. What are the characteristic features of chromosomal microarrays?

The key characteristic features of chromosomal microarray tests are:

Using high-resolution technology to examine areas of the genome linked to hereditary disorders
Analytical sensitivity for low-level mosaics detection.
Reproducible data using difficult samples, such as FFPE.