CPT® Code 81243

FMR1 (fragile X messenger ribonucleoprotein 1) (eg, fragile X syndrome, X-linked intellectual disability [XLID]) gene analysis; evaluation to detect abnormal (eg, expanded) alleles

The CPT® Code 81243 pertains to the molecular genetic testing of the FMR1 gene, which is crucial for diagnosing conditions such as Fragile X syndrome and X-linked intellectual disability (XLID). This gene is located on the X chromosome and is responsible for coding the fragile X messenger ribonucleoprotein 1 (FMRP). The FMRP is essential for the normal development of synapses in the brain, particularly in processes related to synaptic plasticity, which is vital for learning and memory. A properly functioning FMR1 gene produces a non-mutated protein that is necessary for cognitive development and female reproductive health. Mutations in the FMR1 gene can lead to a range of disorders, including Fragile X syndrome, which is recognized as one of the most prevalent inherited forms of intellectual disability. The impact of these mutations tends to be more pronounced in males compared to females. The analysis performed under CPT® Code 81243 specifically aims to detect abnormal or expanded alleles of the FMR1 gene. The normal sequence of the FMR1 gene consists of a repeating pattern of CGG (cytosine-guanine-guanine) with interruptions of AGG (alanine-guanine-guanine), repeating between 4 and 44 times. When the CGG segment repeats between 45 and 54 times, individuals are considered to be at borderline risk for expressing characteristics of Fragile X syndrome. A pre-mutation, characterized by 55 to 200 repeats, can increase the risk of developing associated conditions such as Fragile X-associated tremor/autism syndrome (FXTAS) and premature ovarian failure. Full mutation occurs when the CGG segment exceeds 200 repetitions, leading to significant gene instability and potential silencing of the non-mutated FMR1 gene, which manifests as Fragile X syndrome. The implications of these mutations are profound, affecting cognitive abilities, reproductive health, and overall quality of life for those impacted.