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Behavioural biomarkers of typical Rett syndrome: moving towards early identification
Christa Einspieler1, Michael Freilinger2, Peter B Marschik3,4
1Research Unit iDN, interdisciplinary Developmental Neuroscience, Institute of Physiology, Center for Physiological Medicine, Medical University of Graz, Harrachgasse 21/5, 8010, Graz, Austria. christa.einspieler@medunigraz.at.
Insights
Early detection of Rett syndrome (RTT) is possible through infant behavioral biomarkers. Abnormal movements, vocalizations, and stereotypies appear from birth, challenging the notion of a normal developmental start.
Area of Science:
- Neuroscience
- Developmental Pediatrics
- Genetics
Background:
- Rett syndrome (RTT) is traditionally thought to have a period of normal development, but emerging evidence suggests early abnormalities.
- Infants with RTT exhibit behavioral peculiarities and motor/vocal differences from birth.
Purpose of the Study:
- To identify specific behavioral biomarkers for early pinpointing of Rett syndrome in infants.
- To challenge the established understanding of RTT's developmental trajectory.
Main Methods:
- Observational analysis of infant behavior in individuals with RTT.
- Characterization of early motor, vocal, and gestural patterns.
- Identification of repetitive behaviors and stereotypies.
Main Results:
- Abnormal spontaneous general movements are present from birth.
- Vocalizations include proto-vowel/consonant alternations, breathy voice, and pressed/high-pitched sounds, alongside limited canonical babbling.
- Limited gestural repertoire, delayed/absent milestones, abnormal blinking, tongue protrusion, bizarre smiling, and early stereotypies (body/hand) are observed within the first year.
Conclusions:
- Behavioral peculiarities and abnormalities are evident from birth in RTT, not after a period of normal development.
- A specific set of behavioral biomarkers is being defined for early RTT identification.
- These findings necessitate a re-evaluation of RTT's early developmental course.
Abstract:
The dynamic course of Rett syndrome (RTT) is still said to begin with a period of apparently normal development although there is mounting evidence that individuals with RTT show behavioural peculiarities and abnormalities during their infancy. Their spontaneous general movements are abnormal from birth onwards. Normal cooing vocalisation and canonical babbling (if at all required) are interspersed with abnormalities such as proto-vowel and proto-consonant alternations produced on ingressive airstream, breathy voice characteristics, and pressed or high-pitched vocalisations. The gestural repertoire is limited. Certain developmental motor and speech-language milestones are not at all acquired or show a significant delay. Besides abnormal blinking, repetitive and/or long lasting tongue protrusion, and bizarre smiling, there are already the first body and/or hand stereotypies during the first year of life. We are currently on a promising way to define a specific set of behavioural biomarkers pinpointing RTT.
