Marina Picillo1, Sara Scannapieco2, Alessandro Iavarone3, Monia Ginevrino4,5, Enza Maria Valente6,7, Paolo Barone8. 1. Center for Neurodegenerative diseases (CEMAND), Department of Medicine, Surgery and Dentistry, Neuroscience section, University of Salerno, Baronissi, Salerno, Italy. mpicillo@unisa.it. 2. Center for Neurodegenerative diseases (CEMAND), Department of Medicine, Surgery and Dentistry, Neuroscience section, University of Salerno, Baronissi, Salerno, Italy. 3. Neurological and Stroke Unit, Centro Traumatologico Ortopedico Hospital AORN "Ospedali dei Colli", Naples, Italy. 4. Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Roma, Italy. 5. Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, Rome, Italy. 6. Department of Molecular Medicine, University of Pavia, Pavia, Italy. 7. IRCCS Mondino Foundation, Pavia, Italy. 8. Center for Neurodegenerative diseases (CEMAND), Department of Medicine, Surgery and Dentistry, Neuroscience section, University of Salerno, Baronissi, Salerno, Italy. pbarone@unisa.it.
Abstract
BACKGROUND: Glucocerebrosidase (GBA) heterozygous variants are the most important genetic risk factor for the development of alpha-synucleinopathies (i.e., Parkinson's disease and Dementia with Lewy Bodies). Herein, we report for the first time on a patient with a clinical diagnosis of Posterior Cortical Atrophy, carrier of the common GBA heterozygous variant N370S (c.1226A > G). CASE PRESENTATION: A 44-year-old woman with positive familial history for Dementia with Lewy Bodies disclosed three related signs characterizing the Balint's syndrome: ocular apraxia, optic ataxia and simultanagnosia. Over 2-year follow up, overt gaze apraxia (psychic paralysis of gaze) appeared leading to functional blindness. Given her young age at onset and positive familial history, she underwent a next-generation-sequencing (NGS) based screening of a panel of 32 genes related to neurodegenerative conditions within the ANAMNESYS (An origiNal Approach to study faMiliarity in NEurodegenerative SYndromeS) study. NGS demonstrated the N370S variant in the GBA gene (rs76763715), confirmed by Sanger sequencing. This is a relatively common variant, with predicted mild impact, already reported to occur in 2.4% of PD Italian patients; however, neither this nor other GBA variants have ever been reported to date in patients with Posterior Cortical Atrophy. Glucocerebrosidase activity was investigated and found to be significantly reduced (4.72 nmol/h/mg) compared to healthy controls as well as patients affected by neurodegenerative diseases, further supporting pathogenicity of the GBA variant. CONCLUSIONS: We report on a patient with a clinical diagnosis of Posterior Cortical Atrophy, carrier of the GBA heterozygous variant N370S (c.1226A > G; p.Asn409Ser) determining reduced GCase activity. This report also confirms the role of NGS-based targeted gene analysis in detecting peculiar clinical phenotypes associated with known pathogenic mutations and reinforces the knowledge that carriers of genetic variants often present phenotypic overlaps across different neurodegenerative syndromes, highlighting the limitations of current clinical diagnostic criteria in defining boundaries between distinct conditions and the difficulties of clinicians in reaching the best clinical diagnosis.
BACKGROUND:Glucocerebrosidase (GBA) heterozygous variants are the most important genetic risk factor for the development of alpha-synucleinopathies (i.e., Parkinson's disease and Dementia with Lewy Bodies). Herein, we report for the first time on a patient with a clinical diagnosis of Posterior Cortical Atrophy, carrier of the common GBA heterozygous variant N370S (c.1226A > G). CASE PRESENTATION: A 44-year-old woman with positive familial history for Dementia with Lewy Bodies disclosed three related signs characterizing the Balint's syndrome: ocular apraxia, optic ataxia and simultanagnosia. Over 2-year follow up, overt gaze apraxia (psychic paralysis of gaze) appeared leading to functional blindness. Given her young age at onset and positive familial history, she underwent a next-generation-sequencing (NGS) based screening of a panel of 32 genes related to neurodegenerative conditions within the ANAMNESYS (An origiNal Approach to study faMiliarity in NEurodegenerative SYndromeS) study. NGS demonstrated the N370S variant in the GBA gene (rs76763715), confirmed by Sanger sequencing. This is a relatively common variant, with predicted mild impact, already reported to occur in 2.4% of PD Italian patients; however, neither this nor other GBA variants have ever been reported to date in patients with Posterior Cortical Atrophy. Glucocerebrosidase activity was investigated and found to be significantly reduced (4.72 nmol/h/mg) compared to healthy controls as well as patients affected by neurodegenerative diseases, further supporting pathogenicity of the GBA variant. CONCLUSIONS: We report on a patient with a clinical diagnosis of Posterior Cortical Atrophy, carrier of the GBA heterozygous variant N370S (c.1226A > G; p.Asn409Ser) determining reduced GCase activity. This report also confirms the role of NGS-based targeted gene analysis in detecting peculiar clinical phenotypes associated with known pathogenic mutations and reinforces the knowledge that carriers of genetic variants often present phenotypic overlaps across different neurodegenerative syndromes, highlighting the limitations of current clinical diagnostic criteria in defining boundaries between distinct conditions and the difficulties of clinicians in reaching the best clinical diagnosis.
Entities:
Keywords:
Case report; GBA; Genetics; Parkinsonism; Posterior cortical atrophy
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