Between five and 10 patients had juvenile neuronal ceroid lipofuscinosis (JNCL), PTRHD1, RAB39B, X‐linked parkinsonism with spasticity, Alexander disease, dopa‐responsive dystonia‐parkinsonism (NR4A2), Fragile‐X syndrome or spastic paraplegia type 15 (SPG15). The gene discussed is PTRHD1; the disease is Alexander disease.