Microtia atresia is a rare inherited condition that causes the external auditory canal to become blocked. Unlike most congenital disabilities, there is no known cure. However, remarkable progress has been made in reconstructive surgery for this condition. In this article, we will discuss the HOXA2 mutation, genetic syndromes associated with microtia atresia, and the treatment options available for the patient.
HOXA2 mutations
The HOXA2 gene has several rare mutations. Two are predicted to be pathogenic and are associated with severe microtia atresia. The first mutation is highly conserved among species, whereas the second mutation is relatively conserved. The first mutation affects an amino acid within the laminin N-terminal domain. Both mutations result in severe microtia.
The HOX genes encode a group of 60 amino acid proteins that are crucial for sensorimotor circuitry. Mutations cause microtia atresia in HOXA1 or HOXA2. These proteins regulate related biological processes by binding to a 5′-flanking sequence. However, HOXA2 mutations have been linked to various cancer types, and downregulation of HOXA4 in lung cancer cells inhibits their growth and invasion.
Although the evidence that HOXA2 mutations cause Micronesia atresia is robust, further proof will come from identifying additional patients with the faulty gene and functional assays of the mutant protein’s DNA-binding activity. The researchers believe that the HOXA2 gene has a role in developing the palate.
Genetic syndromes associated with microtia atresia
There are several genetic syndromes associated with microtia atresia. Most of these syndromes have a pronounced Mendelian inheritance pattern, but some are multifactorial. No known genes cause isolated microtia, but some have been implicated in associated microtia syndromes. This review summarizes the current literature regarding microtia atresia and discusses its etiology.
In children, isolated microtia usually affects only one side of the ear and is more common in boys. This condition affects one in every 500 births, with the right ear more commonly affected. Bilateral microtia occurs in one in every ten babies. The syndrome is most common in Asian populations, with African Americans least likely to be involved. In addition, it is associated with Treacher Collins syndrome, Branchio Oto Renal Syndrome, and Nager syndrome.
Several genetic syndromes have been implicated in the etiology of microtia atresia. In a study of 27 severe cases, 65 rare heterozygous mutations in 42 genes were identified. Among these, DCHS1 was strongly implicated in the development of microtia-atresia. In addition, several low-frequency and common variants association studies have also identified a genetic mutation in this gene. However, these results do not prove a causal association.
Frequency of consultation for microtia atresia
Microtia is a rare congenital condition in which the outer part of the ear does not develop properly during early pregnancy. This condition is a random event that cannot be attributed to the mother’s actions, genetics, or environmental factors. However, associated factors may contribute to the occurrence of microtia. Consultation for microtia is therefore essential for a variety of reasons.
The IMAW guidelines for the treatment of microtia atresia are based on the opinions of a multidisciplinary group. Therefore, they must be interpreted by practitioners using their medical judgment. Before undergoing microtia atresia surgery, patients must be monitored closely and referred for a consultation if new bone growth occurs during puberty.
Microtia atresia is typically found in boys. One ear is more commonly affected than the other. Bilateral microtia affects one in every ten children. One in 8,000 to ten children is born with microtia, and there is a high chance that the condition will be passed on in a family. Therefore, consultation frequency for microtia atresia is often higher in families where one person has the disease.
Treatment options
While microtia atresia can lead to many difficulties in the child’s development, the good news is that there are several treatment options available. The first and most popular option is rib cartilage reconstruction, which involves harvesting tissue from the child’s chest and using it to build an outer ear. However, this surgery is not an option for infants and children younger than eight years since the process can cause chest deformity.
Another option is canal reconstruction surgery if the atresia is not severe enough to warrant a skin flap. Porous polyethylene microtia repair may be performed in children under five years of age. However, before completing a polyethylene repair, the child must have a canal reconstruction. In addition, if the surgery is performed after the polyethylene graft has been implanted, there is a risk of infection or extrusion of the graft.
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