A 2 year old female child, normal at bih, having normal early development, now presents with microcephaly, regression of acquired language & motor milestone along with abnormal stereotypic hand wringing movements. Most likely diagnosis is?

Rett syndrome:cause of acquired microcephaly X linked dominant inheritance MC gene involve MECP2 gene MC in females Normal head circumference at bih Deceleration of head growth. Developmental delay followed by loss of purposeful hand movement with development of stereotypic hand wringing movement Asperger syndrome:characterized by significant difficulties in social inheritance and nonverbal communication along with restricted and repetitive patterns of behavior and interest. Metachromatic Dystrophy: lysosomal storage disease that causes progressive demyelination of central (white matter) and peripheral nervous system.