Sensory processing ‘atypical’ in Rett and MDS patients, study finds

Survey of caregivers shows hypersensitivity to external stimuli

Andrea Lobo, PhD avatar

by Andrea Lobo, PhD |

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Children with the MECP2 gene-related disorders Rett syndrome and MECP2 duplication syndrome (MDS) experience atypical sensory processing, according to a recent study.

Deficits in the MeCP2 protein chiefly cause Rett syndrome, whereas MDS occurs due to duplication of the chromosomal region containing the MECP2 gene. Unusual sensory effects were more pronounced in MDS patients, and they particularly related to a higher sensitivity to external stimuli.

“Data from this study may help clinicians in managing individuals with MDS and [Rett],” the researchers wrote, adding that their work “paves the path toward [a] better understanding of sensory phenotypes in MDS versus [Rett].”

The study, “Sensory experiences questionnaire unravels differences in sensory profiles between MECP2-related disorders,” was published in Autism Research.

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Rett syndrome is mainly caused by mutations in the MECP2 gene that impair the production or activity of MeCP2, a protein that regulates the activity of other genes. The loss of MeCP2 affects the growth and connectivity of neurons (nerve cells), leading to Rett symptoms.

Rett and MDS patients have many overlapping symptoms, including features of autism — a developmental disorder that affects how people interact with others, learn, and behave.

But the specific sensory changes in each disorder are not yet well known, according to the scientists. Also, “few studies have dissected the differences between these opposite gene dosage disorders,” they wrote.

To investigate, researchers in the U.S. conducted a study combining in-person and online surveys answered by caregivers of 50 children with Rett and 122 with MDS.

The mean age of Rett patients, all female, was 13.6 years, whereas MDS patients were mainly male (98%) and significantly younger (mean age of 9.8 years).

Specifically, the team used the Sensory Experiences Questionnaire, chosen because it has been validated in people of the same age range as the study’s participants, is easy to administer, and is sensitive to abnormalities in sensory perception. Higher scores indicate more pronounced sensory symptoms.

The total score was higher in both Rett (77.9) and MDS patients (86) than the upper limit of a typical score (74), with MDS patients being significantly more affected than those with Rett.

This difference between the disease groups was mainly driven by hypersensitivity — excessive sensitivity when exposed to external stimuli — and sensory seeking, the need to seek additional sensory input.

Both social and nonsocial stimuli showed differences between the groups. Sensory symptoms also were higher in MDS children in the areas of tactile and vestibular sensory processing, needed to maintain balance and movement when moving.

However, no significant differences were observed regarding processing of hearing, visual, smell, or taste stimuli. Also, sensory scores did not change with age.

Sensory symptom scores for MDS patients were closer to those in idiopathic (of unknown cause) autism individuals, while Rett scores were “nearer” to the typical range, the scientists noted.

“These findings reveal a first insight into sensory processing abnormalities caused by a dosage sensitive gene and may ultimately help guide therapeutic approaches for these disorders,” the researchers wrote.