title: Massive SCA7 expansion detected in a 7-month-old male with hypotonia, cardiomegaly, and renal compromise.
abstract: Infantile spinocerebellar ataxia type 7 (SCA7) is phenotypically different from the child-onset and adult-onset cases, presenting as a multisystem disorder associated with pathologically large CAG trinucleotide repeat sequences. We describe a case study of a male who presented at 5 months of age with marked motor delay, failure to thrive, and a patent ductus arteriosus. He later developed renal failure of uncertain aetiology. The infant became progressively hypotonic, and cardiac and renal function deteriorated further; he died at the age of 11 months of multisystem failure. Family history revealed a diagnosis of SCA7 in the infant's father, paternal grandfather, and aunt. DNA analysis confirmed an expanded trinucleotide repeat in the SCA7 locus of about 240 repeats, suggesting a diagnosis of infantile SCA7. Striking anticipation is seen in SCA7, particularly with paternal transmission. The underlying pathophysiological processes seem to involve alteration in transcriptional regulation and a selective neuronal vulnerability to the widely distributed abnormal protein product. This case report reviews the current literature relating to infantile SCA7 and raises awareness of this rare but important phenotype.
authors.affiliation: Paediatric Neurosciences, Guy's & St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Andrea
authors.initials: A
authors.lastname: Whitney
authors.forename: Ming
authors.initials: M
authors.lastname: Lim
authors.forename: Dipak
authors.initials: D
authors.lastname: Kanabar
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Lin
mesh_terms: D000067719:Ataxin-7; D006332:Cardiomegaly / Q000150:complications / Q000235:genetics* / Q000473:pathology; D006801:Humans; D007223:Infant; D008297:Male; D009123:Muscle Hypotonia / Q000150:complications / Q000235:genetics* / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D051437:Renal Insufficiency / Q000150:complications / Q000235:genetics* / Q000473:pathology; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*
chemical_list: C000593829:ATXN7 protein, human; D000067719:Ataxin-7; D009419:Nerve Tissue Proteins