Rett syndrome: a wide clinical and autonomic picture.
BACKGROUND
Rett Syndrome is a neurodevelopmental disorder almost exclusively affecting females, characterized by a broad clinical spectrum of signs and symptoms and a peculiar course. The disease affects different body systems: nervous, muscolo-skeletal, gastro-enteric. Moreover, part of the symptoms are related to the involvement of the autonomic nervous system. In the Tuscany Rett Center at Versilia Hospital, we collected data from 151 subjects with a clinical diagnosis of classical or variant RTT syndrome. For each subject, we assessed the severity of the condition with clinical-rating scales (ISS, PBZ), we quantified the performance of the autonomic nervous system, and we performed genetic analysis. We used multivariate statistical analysis of the data to evaluate the relation between the different clinical RTT forms, the cardiorespiratory phenotype, the different genetic mutations and the severity of the clinical picture. Individuals were classified according to existing forms: Classical RTT and three atypical RTT: Z-RTT, Hanefeld, Congenital. A correlation between C-Terminal deletions and lower severity of the clinical manifestations was evident, in the previous literature, but, considering the analysis of autonomic behaviour, the original classification can be enriched with a more accurate subdivision of Rett subgroups, which may be useful for early diagnosis.


RESULTS
Present data emphasize some differences, not entirely described in the literature, among RTT variants. In our cohort the Z-RTT variant cases show clinical features (communication, growth, epilepsy and development), well documented by specific ISS items, less severe, if compared to classical RTT and show autonomic disorders, previously not reported in the literature. In this form epilepsy is rarely present. In contrast, Hanefeld variant shows the constant presence of epilepsy which has an earlier onset In Hanefeld variant the frequency of apneas was rare and, among the cardiorespiratory phenotypes, the feeble type is lacking.


CONCLUSIONS
A quantitative analysis of the different autonomic components reveals differences across typical and atypical forms of RTT that leads to a more accurate classification of the groups. In our cohort of RTT individuals, the inclusion of autonomic parameter in the classification leads to an improved diagnosis at earlier stages of development.
Tuscany Rett Center, Versilia Hospital, USL Toscana Nord Ovest, Pisa, Italy. giorgio.pini@uslnordovest.toscana.it.|Versilia Hospital, via Aurelia 335, Camaiore, Tuscany, Italy. giorgio.pini@uslnordovest.toscana.it.
G
G
Pini
Medical Genetics UOL, Ferrara University Hospital, Ferrara, Italy.
S
S
Bigoni
Tuscany Rett Center, Versilia Hospital, USL Toscana Nord Ovest, Pisa, Italy.
L
L
Congiu
CNR, Istituto di Fisiologia Clinica, Pisa, Italy.
A M
AM
Romanelli
Tuscany Rett Center, Versilia Hospital, USL Toscana Nord Ovest, Pisa, Italy.
M F
MF
Scusa
Tuscany Rett Center, Versilia Hospital, USL Toscana Nord Ovest, Pisa, Italy.
P
P
Di Marco
Tuscany Rett Center, Versilia Hospital, USL Toscana Nord Ovest, Pisa, Italy.
A
A
Benincasa
Tuscany Rett Center, Versilia Hospital, USL Toscana Nord Ovest, Pisa, Italy.
P
P
Morescalchi
Medical Genetics UOL, Ferrara University Hospital, Ferrara, Italy.
A
A
Ferlini
CNR, Istituto di Fisiologia Clinica, Pisa, Italy.
F
F
Bianchi
Neuropsychiatric Genetics, Trinity Center for Health Science, St James Hospital, D8 Dublin, Ireland.
D
D
Tropea
Tuscany Rett Center, Versilia Hospital, USL Toscana Nord Ovest, Pisa, Italy.
M
M
Zappella
ARTT-NOS: Atypical RTT-not otherwise specified; CDKL5: Cyclin dependent kinase-like 5; FOXG1: Forkhead box G1; MECP2: Methyl CpG binding protein 2; RTT: Rett syndrome; Z-RTT: Preserved speech variant or “Zappella variant”
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