Rett syndrome is a complex neurodevelopmental disorder, caused by mutations in MECP2 gene. At present, around 900 different variations, both benign and pathogenic of the gene are known. Different mutations can lead to variable levels of severity, different clinical features and may be associated with variable demographic profile. We present here a case study of 6 Rett Syndrome cases, a part of "Genetics in Autism" research study and their genotype-phenotype profile. The study includes two novel variants, c.23_27del in exon1 and c.538C>T variant (male mosaic) known in females but not in males. Although it is a small sample size, the study highlights the importance of genetic tests and counselling in children with features of autism spectrum disorder.