Which early‑childhood syndrome, especially in females, is characterized by stereotyped repetitive hand‑wringing or hand‑clapping movements and nocturnal or daytime bruxism?

Rett Syndrome

The syndrome described is Rett syndrome, an X-linked neurodevelopmental disorder predominantly affecting females, characterized by stereotyped hand-wringing or hand-clapping movements and bruxism (teeth grinding), typically manifesting after 6-18 months of initially normal development. 1, 2, 3

Core Diagnostic Features

Rett syndrome presents with four cardinal features that distinguish it from other neurodevelopmental disorders:

• Stereotyped repetitive hand movements (hand-wringing, hand-washing, or hand-clapping) that develop after loss of purposeful hand skills 1, 2, 3
• Loss of spoken language after a period of normal language development 1, 2, 4
• Gait abnormalities including wider-based stance and balance difficulties 5, 4
• Deceleration of head growth occurring before 4 years of age 1, 2

Additional Characteristic Features

Bruxism (teeth grinding) is one of the most frequent oral manifestations in Rett syndrome:

• Bruxism occurs both during daytime and nocturnal periods in affected individuals 3, 6, 7
• The combination of hand stereotypies, bruxism, hyperventilation, and seizures in early childhood helps distinguish Rett syndrome from infantile autism 3
• Other oral findings include mouth breathing, tongue thrusting, anterior open bite, and masseteric hypertrophy 7

Temporal Pattern and Regression

The hallmark temporal sequence involves normal early development followed by regression:

• Development appears normal during the first 6-18 months of life 3, 4
• Progressive loss of intellectual functioning, fine motor skills, and gross motor skills follows the initial normal period 3
• Simultaneous regression of both motor and language skills is typical and helps differentiate from autism 3
• Repeated abnormal behaviors including head banging may accompany the hand stereotypies and bruxism 5

Genetic Basis and Sex Distribution

Rett syndrome has a clear genetic etiology:

• Most cases are caused by mutations in the MECP2 gene (methyl-CpG-binding protein 2) 1, 2, 5, 4
• The disorder predominantly affects females due to its X-linked nature 1, 2, 4
• Males can carry the same mutations but present with different clinical manifestations ranging from fatal encephalopathy to nonspecific X-linked intellectual disability 1, 2

Diagnostic Confirmation

Genetic testing for MECP2 mutations is the definitive diagnostic test:

• MECP2 genetic testing should be performed when clinical features suggest Rett syndrome 2, 5
• Brain MRI is recommended to evaluate for structural abnormalities and rule out other causes of regression 2
• EEG assessment is indicated to evaluate for seizure activity, which commonly accompanies the disorder 2, 5
• If MECP2 testing is negative but clinical suspicion remains high, broader genetic testing via chromosomal microarray should be pursued 2

Key Differentiating Points from Autism

Several features help distinguish Rett syndrome from autism spectrum disorder:

• The simultaneous regression of both motor and language skills is more characteristic of Rett syndrome than autism 3
• The specific pattern of hand stereotypies (wringing/washing/clapping) differs from the broader range of stereotypies seen in autism 1, 3
• Deceleration of head growth is a specific feature of Rett syndrome not typically seen in autism 1, 2
• Infantile autism is the most common incorrect diagnosis made for children with Rett syndrome 3