X linked alpha thalassaemia mental retardation (ATR-X) syndrome is an inherited neurological disorder affecting males. Females with one affected gene are carriers of the disorder. The clinical picture associates profound developmental delay, facial dysmorphism, genital malformations and alpha thalassaemia. A mild microcytic anaemia can be found on the blood cell count. It is usually due to alpha thalassaemia trait and can associate trace amounts of H haemoglobin, specific inclusions seen into red cells with special dyes (golf balls red cells). The alpha globin genes are normal. The gene responsible (the ATRX gene) is located on the X chromosome and encodes a protein responsible for the regulation of other genes among which, the alpha globin genes.  Genetic counselling can be offered to families.