From the Medical Literature - July 1998

Record  1
   
  Word  learning  in  a  special  population:  do individuals with Williams
syndrome obey lexical constraints?
  Stevens T; Karmiloff-Smith A
  University College London.
  J Child Lang (ENGLAND)   Oct 1997,  24 (3) p737-65,  ISSN 0305-0009
Journal Code: HP1
  Languages: ENGLISH
  Document type: JOURNAL ARTICLE

  Williams syndrome (WS), a rare neurodevelopmental disorder, is of special
interest   to   developmental   psycholinguists   because   of  its  uneven 
linguistico-cognitive  profile  of  abilities and deficits. One proficiency 
manifest  in  WS  adolescents  and  adults is an unusually large vocabulary 
despite serious deficits in other domains. In this paper, rather than focus 
on   vocabulary  size,  we  explore  the  processes  underlying  vocabulary 
acquisition,  i.e.  how  new  words are learned. A WS group was compared to 
groups  of  normal  MA-matched  controls  in  the  range  3-9 years in four 
different  experiments  testing  for  constraints on word learning. We show 
that  in  construing  the meaning of new words, normal children at all ages 
display   fast   mapping  and  abide  by  the  constraints  tested:  mutual 
exclusivity,  whole  object  and taxonomic. By contrast, while the WS group 
showed  fast  mapping  and  the mutual exclusivity constraint, they did not 
abide  by  the  whole  object  or taxonomic constraints. This suggests that 
measuring  only the size of WS vocabulary can distort conclusions about the 
normalcy  of WS language. Our study shows that despite equivalent behaviour 
(i.e.  vocabulary  test  age),  the  processes underlying how vocabulary is 
acquired  in  WS  follow  a  somewhat  different  path  from that of normal 
children  and  that  the  atypically  developing brain is not necessarily a 
window on normal development.
   
Record  2
   
  [Williams  syndrome:  a window to the development of cognitive and neural
processes]
  La  sindrome di Williams: una finestra aperta sullo sviluppo dei processi
cognitivi e neurali.
  Capirci O; Queyras A; Alleva E; Volterra V
  Istituto di Psicologia, Consiglio Nazionale delle Ricerche, Roma.
  Ann Ist Super Sanita (ITALY)   1997,  33 (2) p259-66,  ISSN 0021-2571
Journal Code: 5BP
  Languages: ITALIAN   Summary Languages: ENGLISH
  Document  type:  JOURNAL  ARTICLE;  REVIEW;  REVIEW,  TUTORIAL    English
Abstract

  Williams  syndrome  (SW)  is  a rare (2-5/100,000) genetic human disorder
characterised  by a typical facies and mental retardation with a deficit in 
the  visuo-spatial  cognitive  function  and  a  relative  preservation  of 
linguistic  abilities.  This syndrome also includes morphological anomalies 
and  metabolic-functional  impairments,  likely  deficits in the pattern of 
brain  ontogenesis.  Neuropsychological  and  somatic  features  of  the SW 
individuals  are illustrated, and the correspondent genetic bases, recently 
identified,  are presented. The possible role of NGF (nerve growth factor), 
a  particular neurotrophin involved in the development of brain cholinergic 
system  and  the  associated behavioural functions, in the aetiology of the 
typical  mental  retardation  of  SW  patients,  is  critically  discussed. 
Prospect   of   researches,   including  the  identification  of  potential 
neurobiological   markers  and  the  definition  of  appropriate  cognitive 
profiles  of the SW, in order to precociously diagnose this syndrome, and a 
more  thorough  investigation of factors affecting phenotypic expression of 
this  genetically  determined  pathological  condition,  are reviewed.  (73
 Refs.)
   
Record  3
   
  FISH analysis in patients with clinical diagnosis of Williams syndrome. 
  Elcioglu N; Mackie-Ogilvie C; Daker M; Berry AC
  Division of Medical and Molecular Genetics, UMDS, Guy's Hospital, London,
UK.
  Acta Paediatr (NORWAY)   Jan 1998,  87 (1) p48-53,  ISSN 0803-5253
Journal Code: BGC
  Languages: ENGLISH
  Document type: JOURNAL ARTICLE; REVIEW; REVIEW, MULTICASE

  Williams  syndrome  is  a  rare neurodevelopmental disorder with variable
phenotypic  expression and a contiguous gene syndrome caused by deletion of 
the  elastin  gene.  In  our  study,  hemizygosity at the elastin locus was 
investigated  using FISH analyses in 16 sporadic cases with a firm clinical 
diagnosis  of  Williams  syndrome,  and  the  characteristic  features were 
evaluated.  Fourteen  patients  were  found  to  have  deletions; 2 further 
patients  did  not  have  deletions  of  the elastin gene, but did have the 
clinical  features. The presence of two copies of the elastin gene locus in 
a  patient  does  not  rule  out  Williams  syndrome  as a diagnosis. Since 
deletion  of  the elastin gene, which continues to be a useful confirmatory 
diagnostic  test,  cannot  account  for  several features found in Williams 
syndrome, the non-deletion patients will be valuable in further delineation 
of  the critical region responsible for the Williams syndrome phenotype.  ( 
20 Refs.)

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