LAUSR

We read with great interest the manuscript by Videira and colleagues, about the diagnosis of Aicardi-Goutières syndrome (AGS) in adults, and we would like to contribute with 2 more cases of an ongoing study in southern Brazil. Two sisters with nonconsanguineous parents were evaluated at a tertiary center in Brazil. The first patient was a 20-year-old woman that presented with spastic paraplegia since the age of 3 and epilepsy with generalized tonic-clonic seizures controlled with carbamazepine. The mother reported that the patient had acquired a gait before she started showing motor symptoms. At the time of the evaluation, the patient walked independently, but was unable to run. She did not have cognitive impairment (scored 29/30 points on the MiniMental State Examination), neither did she have psychiatric symptoms or oculomotor changes. A computerized tomography scan showed linear and “spot-like” calcifications in the bilateral lentiform nucleus (Fig. 1). Magnetic resonance imaging showed mild diffuse cerebral atrophy and cavum septum pellucidum. The second patient was her 30-year-old sister, whose clinical picture was more severe. This patient had an important neuromotor development delay and was never able to walk. At the time of examination, the patient was restricted to a wheelchair because of generalized dystonia and she had severe mental retardation and refractory epilepsy. After an initial investigation, the patients underwent a total sequencing of exoma that revealed the presence of the homozygous variant c.529G> A, p.Ala177Thr in exon 7 of the RNASEH2B gene. More than 30% of AGS patients have pathological variants of the RNASEH2B gene in the published case series. There are more than 20 pathological variants described for RNASEH2B, the most frequent being the replacement of amino acids c.529G> A (p.Ala177Thr) from exon 7, the same genotype found in the patient. The classic phenotype presents as a progressive encephalopathy and sometimes even death in the first years of life. The first patient presented began to show spasticity symptoms in the lower limbs at the age of 3, she did not have a clinically cognitive impairment, and she still walked without assistance at the age of 20. Few patients with pathological