Expanding SPTAN1 monoallelic variant associated disorders: From epileptic encephalopathy to pure spastic paraplegia and ataxia

PURPOSE

Nonerythrocytic αII-spectrin (SPTAN1) variants have been previously associated with intellectual disability and epilepsy. We conducted this study to delineate the phenotypic spectrum of SPTAN1 variants.

METHODS

We carried out SPTAN1 gene enrichment analysis in the rare disease component of the 100,000 Genomes Project and screened 100,000 Genomes Project, DECIPHER database, and GeneMatcher to identify individuals with SPTAN1 variants. Functional studies were performed on fibroblasts from 2 patients.

RESULTS

Statistically significant enrichment of rare (minor allele frequency < 1 × 10-5) probably damaging SPTAN1 variants was identified in families with hereditary ataxia (HA) or hereditary spastic paraplegia (HSP) (12/1142 cases vs 52/23,847 controls, p = 2.8 × 10-5). We identified 31 individuals carrying SPTAN1 heterozygous variants or deletions. A total of 10 patients presented with pure or complex HSP/HA. The remaining 21 patients had developmental delay and seizures. Irregular αII-spectrin aggregation was noted in fibroblasts derived from 2 patients with p.(Arg19Trp) and p.(Glu2207del) variants.

CONCLUSION

We found that SPTAN1 is a genetic cause of neurodevelopmental disorder, which we classified into 3 distinct subgroups. The first comprises developmental epileptic encephalopathy. The second group exhibits milder phenotypes of developmental delay with or without seizures. The final group accounts for patients with pure or complex HSP/HA.

[Acquired cerebral toxoplasmosis in an non-immunosuppressed child]

BACKGROUND

Postnatally acquired toxoplasmosis is relatively common as an unapparent infection. When there are severe clinical manifestations such as encephalitis, pneumonia and myocarditis, the patient should be checked for immunocompetence deficiencies.

CASE REPORT

A two-year old girl living in French Guyana suffered from acute respiratory distress due to interstitial pneumonia plus pericarditis that was treated by closed pericardial aspiration. Palsies of four limbs and chorioretinitis gradually appeared. The CSF protein content was elevated, 1 g/l, but the number of cells was normal. Serologic tests indicated a recent toxoplasma infection; she was given sulfadoxine, pyrimethamine and spiramycin. Her neurologic condition and the persistent antibodies, indicating active disease, led to her transfer to our Department 3 months after the onset of the disease. The CSF contained 47 cells/mm3 and 0.8 g/l proteins. Measurement of both IgM and IgG classes of toxoplasma antibodies showed persistent high titers in the blood and CSF. The CT scan showed numerous calcifications in the brain and hypodense areas in the frontal and parietal lobes. The MRI showed extensive changes. The severity of the disease in this girl led us to study her immune system. It was normal. The girl was given 6-week treatments with pyrimethamine-sulfadiazine for 2 years. This treatment stabilized the disease, but her titers of toxoplasma antibodies remained high.

CONCLUSION

The initial clinical presentation of the disease in this patient and persistent high titers of toxoplasma antibodies, especially of the IgM class, argue against the possibility of congenital toxoplasmosis and favor the diagnosis of acquired disease in a patient who has no immune deficiency.