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Autism is a highly heritable, genetically heterogeneous developmental neuropsychiatric disorder characterized by basic impairments in reciprocal social interaction, delayed-onset and deviant forms of language, and stereotypic behaviors and/or highly restricted interests. While the specific genetic contributors to Autism Spectrum Disorders (ASD) remain largely an arcanum, increasing attention has been paid recently to the etiological role of rare genetic variation. One particularly fruitful area of research has focused on the increased risk for ASD among individuals with single gene disorders including, fragile X, tuberous sclerosis and neurofibromatosis type 1. Spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disease characterised by degeneration of spinal cord motor neurons, atrophy of skeletal muscles, and generalised weakness. It is caused by homozygous disruption of the survival motor neuron 1 (SMN1) gene by deletion, mutation, or conversion. Although no medical treatment is available, investigations have enlightened possible mechanisms underlying the molecular pathogenesis of the disease. Treatment strategies have been developed to use the unique genomic structure of the SMN1 gene region. Here we report a child, initially ascertained for SMA, who was later evaluated for ASD. This observation adds support to the emerging evidence of phenotypic overlap between these conditions and highlights the importance of further study into the neurodevelopmental mechanisms at play in SMA. I.G is a 4 years old Turkish child. She was born at 38 week of gestation with a birth weight of 2.650 grams. Her early motor development wasn't considered within normal limits, including walking by age of 30 months. At the age of 24 months, she was noted by her mother to show markedly delayed speech; uttering only single words, and only in a repetitive fashion. She was referred to our clinic for detailed evaluation. At the time of this assessment, she displayed cognitive retardation with motor impairment including mild difficulty in walking that worsened when she attempted to stand up from sitting position. Physical examination was normal. Deep tendon reşexes were normal too. On laboratory examination, serum creatinine kinase was 100 U/L. EMG showed chronic anterior horn cell involvement following a pattern of reinnervation. The definitive diagnosis of SMA was made based on the clinical and laboratory examination. At that time, the patient was re-evaluated for her autistic symptomatology. She continued to show limited eye contact and little interest in people. She did not speak at all and demonstrated repetitive behaviors and severe reactions to changes in her environment. She fulfilled diagnostic criteria for atypical autism according to the DSM-IV. There was no history of muscular disease or autism or mental retardation in her family. While the co-occurrence of SMA and cognitive delay has been long appreciated, there is not any recognition of an association with autism. It should be noted that additional investigation will be needed to confirm these observations as well as the hypothesis that CNS involvement is a direct consequence of disruption of SMN, or are these conditions caused from the same genetic defect, that we cannot identify.