Surgery usually corrects misaligned eyes in kids with Angelman, study finds
1-year success rate at least 70% regardless of disease-causing mutations
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Surgery aimed at correcting strabismus — a condition in which the eyes are misaligned and do not point in the same direction, causing vision problems — is usually successful in children with Angelman syndrome, according to a new study led by scientists in China.
The one-year success rate was at least 70% for the more than three dozen children undergoing surgery, the researchers noted. Moreover, none of the children required a second operation.
The findings also indicated that strabismus surgery has a similar success rate regardless of the type of Angelman-causing mutation a patient carries. However, the researchers noted, certain eye problems are more common in individuals with chromosomal microdeletions — when there are tiny losses of genetic material in a person’s DNA — than in those with other types of mutations.
The study detailing these results, titled “Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy,” was published in the Journal of American Association for Pediatric Ophthalmology and Strabismus.Â
Angelman syndrome is a genetic disorder caused by mutations in the maternal copy of the UBE3A gene. In the majority of cases, Angelman is specifically caused by a type of mutation called a chromosomal microdeletion — meaning that the piece of DNA containing this gene is missing.
Other types of mutations can also cause Angelman, however, including errors in the UBE3A gene sequence or imprinting defects in which the gene is present but inactive.
Little data on eye surgery outcomes for Angelman patients
Both children and adults with Angelman may experience eye problems, such as strabismus. But the impact of Angelman on eye health has not received much attention from scientists.
Surgery may be used to correct strabismus for people in the general population, but there’s virtually no published data on whether such procedures are typically successful for individuals with Angelman syndrome.
To learn more, researchers from Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University and colleagues from the U.S. analyzed the outcomes seen among 40 children with Angelman syndrome who underwent surgery aimed at correcting strabismus.
The goal was to evaluate the success rate of surgery and provide more details on the specific eye-related manifestations of Angelman. Among the 40 children in this study, about two-thirds carried a chromosomal microdeletion, while the rest had other types of mutations.
Overall, the researchers found that surgery was usually successful for both groups.
Crucially, strabismus surgery achieved stable and comparable alignment outcomes across [different genetic profiles], with no reoperations or significant complications.
Specifically, the success rate at one year post-surgery was 70% among children with deletions and 77% among those with other kinds of mutations. No child needed follow-up surgery.
“Crucially, strabismus surgery achieved stable and comparable alignment outcomes across [different genetic profiles], with no reoperations or significant complications,” the researchers wrote.
Despite similar outcomes after surgery, the researchers noted that certain types of eye problems were more common among children with deletions. Specifically, these children were more often diagnosed with severe astigmatism and/or myopia, disorders that affect how light enters the eye and can typically be corrected with eyeglasses.
1 in 3 children with deletions found to lack color around eye’s pupil
The researchers also found that 1 in 3 children with deletions had severe iris hypopigmentation, or a lack of color in the area around the pupil. This lack of eye color wasn’t seen in any of the children with other mutation types.
According to the team, this loss of eye color in children with deletions is likely caused by loss of OCA2, a gene that helps create eye color and is located very close to UBE3A — meaning it is often lost along with UBE3A when a deletion occurs.
“Patients with [chromosomal microdeletions] demonstrate markedly higher rates of severe iris hypopigmentation and clinically significant astigmatism [and myopia] compared with nondeletion subtypes,” the researchers concluded.
