title: Frequency and phenotypic spectrum of ataxia with oculomotor apraxia 2: a clinical and genetic study in 18 patients.
abstract: Ataxia with oculomotor apraxia type 2 (AOA2) is a newly described autosomal recessive cerebellar ataxia (ARCA) defined by genetic location to 9q34 of three families sharing gait ataxia, oculomotor apraxia and/or elevated alpha-foetoprotein (AFP) levels. We have evaluated 77 families with progressive non-Friedreich ARCA and have identified six families with a phenotype suggestive of AOA2. Linkage was confirmed in all six families, with a maximal lod score of 5.91 at D9S1830. We report the first detailed phenotypic study, including neuropsychological, oculographic and brain imaging investigations, in the largest series of AOA2 patients yet recruited. The mean age at onset was 15.1 +/- 3.8 years. Sensory motor neuropathy (92%) and choreic or dystonic movements (44%) were frequent. Oculomotor apraxia was observed in 56% of patients and characterized by increased horizontal saccade latencies and hypometria. AFP levels were elevated in 100% of the families, making it a useful biological marker. This study shows for the first time that AOA2 can be found in Europe, North Africa and the West Indies, and its relative frequency represents approximately 8% of non-Friedreich ARCA, which is more frequent than ataxia telangiectasia and ataxia with oculomotor apraxia type 1 (AOA1), in our series of adult patients. In adults, AOA2 may be, therefore, the most frequent cause of ARCA identified so far, after Friedreich's ataxia.
authors.affiliation: Fédération de Neurologie, Hôpital Pitié-Salpêtrière AP-HP, Paris, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Le Ber
authors.forename: Naïma
authors.initials: N
authors.lastname: Bouslam
authors.forename: Sophie
authors.initials: S
authors.lastname: Rivaud-Péchoux
authors.forename: João
authors.initials: J
authors.lastname: Guimarães
authors.forename: Ali
authors.initials: A
authors.lastname: Benomar
authors.forename: Céline
authors.initials: C
authors.lastname: Chamayou
authors.forename: Cyril
authors.initials: C
authors.lastname: Goizet
authors.forename: Maria-Ceù
authors.initials: MC
authors.lastname: Moreira
authors.forename: Sandra
authors.initials: S
authors.lastname: Klur
authors.forename: Mohamed
authors.initials: M
authors.lastname: Yahyaoui
authors.forename: Yves
authors.initials: Y
authors.lastname: Agid
authors.forename: Michel
authors.initials: M
authors.lastname: Koenig
authors.forename: Giovanni
authors.initials: G
authors.lastname: Stevanin
authors.forename: Alexis
authors.initials: A
authors.lastname: Brice
authors.forename: Alexandra
authors.initials: A
authors.lastname: Dürr
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001072:Apraxias / Q000235:genetics* / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D020234:Gait Ataxia / Q000235:genetics* / Q000503:physiopathology; D008040:Genetic Linkage; D006239:Haplotypes; D006801:Humans; D008126:Lod Score; D008875:Middle Aged; D009483:Neuropsychological Tests; D015835:Ocular Motility Disorders / Q000235:genetics* / Q000503:physiopathology; D010375:Pedigree; D010641:Phenotype; D000509:alpha-Fetoproteins / Q000032:analysis
chemical_list: D015415:Biomarkers; D000509:alpha-Fetoproteins