The syndrome of X-linked sideroblastic anaemia with ataxia (XLSA/A) is rare. Literature review yields approximately five separate families worldwide. Core neurological features include motor delay, ataxia evident from early childhood, and dysarthria. Neurological features are non-progressive but may advance slowly from the fifth decade. There may be signs of mild spasticity. Patients usually have a mild asymptomatic anaemia or a borderline decreased mean corpuscular volume. Blood film examination showed Pappenheimer bodies. Bone marrow examination shows ring sideroblasts, indicating raised erythrocyte iron. Free erythrocyte protoporphyrin (FEP) concentrations are raised. Heterozygotes may show some mild haematological features but no neurological abnormalities. Haematological features are subtle and can be easily overlooked, and individual patients may not display all the abnormal features. X-linked ataxias are rare and incorrect genetic advice may be given if the diagnostic haematological features of X-linked sideroblastic anaemia are overlooked. Males with early onset ataxia should have a haematological evaluation including a blood film, with a bone marrow examination if abnormal blood count indices and measurement of FEP concentrations raise suspicion. A missense mutation in the ABC7 gene, which maps to Xq13, has been identified in a family with 5 affected males. This gene, an ATP-binding cassette (ABC) transporter, encodes a protein that localizes to the mitochondrial inner membrane and is involved in iron homeostasis. Treatment with pyridoxine has been given to some patients, but has not provided clear benefit.
Last update: October 2004