Which genetic syndrome almost exclusively affects girls and can cause coordination problems and loss of speech?

• A. Rett Syndrome
• B. Turner's Syndrome
• C. Down Syndrome
• D. Fragile X Syndrome

Answer: (A)

Rett syndrome centers on a pattern that almost all affected individuals are girls, due to its X-linked dominant mutation on the MECP2 gene. After a period of typical early development, there is sudden regression in already acquired abilities, especially spoken language, and the emergence of coordination problems or ataxia. Hand-wringing or repetitive hand movements often appear, and loss of purposeful hand use accompanies the decline in communication and motor skills. This combination—female predominance plus regression with loss of speech and motor coordination—makes Rett syndrome the best match for the description.

Turner syndrome involves a sex chromosome anomaly (one X chromosome missing) and presents with short stature and specific physical features, not the neurodevelopmental regression pattern described. Down syndrome features include intellectual disability and characteristic facial and health traits but not the distinct regression of language and motor skills after a period of normal development. Fragile X can cause language delays and social/behavioral differences, but it does not occur almost exclusively in girls and typically does not present the clear regression pattern Rett shows.