Pelizaeus Merzbacher phenotype with epilepsy and autosomal recessive inheritance in two siblings

Introduction: We report the case of two siblings, a daughter and a son of non-consanguineous, healthy parents, who presented with severe developmental retardation in their first year of life and developed epilepsy later on.

Case report: The girl (born in 2002) presented a severe developmental delay and muscle hypotonia in the first year of life. After a temporary arrest in development during the second year of life she exhibited continuous developmental progress. Now at the age of 4 years she is crawling and speaking about 10 words. There is a mild spasticity and no nystagmus. At the age of 19 months a focal epilepsy emerged and was treated successfully with lamotrigine. MRI at the age of 20 months showed severe hypomyelination with myelin seen only in the corticospinal tract, the cerebellar peduncle and the brain steam. A second MRI at the age of 28 months revealed no progress in myelination. Extensive metabolic examinations did not show any abnormal results.

The younger brother (born in 2004) presented with development retardation and muscle hypotonia at the age of 6 months. He developed dislocation of one hip, which needed an open reduction. He showed slow but continuous developmental progress and is now at the age of 16 months able to turn over actively and still has muscle hypotonia. A nystagmus occurred recently. At the age of 13 months a focal epilepsy started, which could not be controlled with lamotrigine yet.

Summary: We conclude that the siblings both have an infantile Pelizaeus Merzbacher phenotype with autosomal recessive inheritance. The occurrence of epilepsy is unusual and to our knowledge not published yet.