Treatment of drop episodes in Coffin–Lowry syndrome

Recurrent Nonconvulsive Status Epilepticus in a Patient with Coffin-Lowry Syndrome

Coffin-Lowry syndrome (CLS) is a rare neurodevelopmental condition caused by heterogeneous mutations in the RPS6KA3 gene on the X chromosome, leading to severe intellectual disability and dysmorphism in men, while women are carriers and only weakly affected. CLS is well known for stimulus-induced drop episodes; however, epilepsy is not commonly reported in this condition. We report on a CLS patient presenting with recurrent episodes of nonconvulsive status epilepticus (NCSE) with generalized epileptic activity, for which investigations did not find any other cause than the patient's genetic condition. This case underlines that the possibility of nonconvulsive epileptic seizures and status epilepticus should, therefore, be considered in those patients. The treatable diagnosis of NCSE may easily be overlooked, as symptoms can be unspecific.

Classic phenotype of Coffin-Lowry syndrome in a female with stimulus-induced drop episodes and a genotype with preserved N-terminal kinase domain

An adolescent female presented with intellectual disability, stimulus-induced drop episodes (SIDEs), facial characteristics that include wide set eyes, short nose with wide columella, full and everted lips with wide mouth and progressive skeletal changes: scoliosis, spondylolisthesis and pectus excavatum. These findings were suggestive of Coffin-Lowry syndrome (CLS), and this was confirmed by the identification of a novel mutation in RPS6KA3, a heterozygous one basepair duplication at nucleotide 1570 (c.1570dupA). This mutation occurs within the C-terminal kinase domain of the protein, and, therefore contradicts the previous report that SIDEs is only associated with premature truncation of the protein in the N-terminal kinase domain or upstream of this domain. As CLS is X-linked, it is unusual for a female to have such a classic phenotype.

Treatment of drop attacks in Coffin-Lowry syndrome with the use of sodium oxybate

Coffin-Lowry syndrome is a well-defined clinical entity classically associated with moderate to severe mental retardation, characteristic facial features, skeletal deformities, and tapering fingers. A characteristic paroxysmal disorder was described in up to 10% patients with Coffin-Lowry syndrome, characterized by sudden loss of muscle tone induced by unexpected tactile or auditory stimuli. These events were given several names, including cataplexy, nonepileptic collapses with atonia, exaggerated startle responses, hyperekplexia, and stimulus-induced drop episodes. Various therapies were undertaken for these drop attacks, including clonazepam, tiagabine, felbamate, selective serotonin reuptake inhibitors, and tricyclics, with variable improvement. We report on a 22-year-old man with Coffin-Lowry syndrome with stimulus-induced drop episodes, who failed therapy with clonazepam, several antiepileptic drugs, and escitalopram, and who was given a trial of sodium oxybate with complete resolution of the drop attacks.