Recurrent interstitial deletions of proximal 18q: a new syndrome involving expressive speech delay.
Most deletions of the long arm of chromosome 18 involve some part of the most distal 30 Mb. We have identified five individuals with cytogenetically diagnosed interstitial deletions that are all proximal to this commonly deleted region. The extent of their deletions was characterized using molecular and molecular cytogenetic techniques. Each participant was assessed under the comprehensive clinical evaluation protocol of the Chromosome 18 Clinical Research Center. Three of the five individuals were found to have apparently identical interstitial deletions between positions of 37.5 and 42.5 Mb (18q12.3-->18q21.1). One individual's deletion was much larger and extended from a more proximal breakpoint position of 23 Mb (18q11.2) to a more distal breakpoint at 43 Mb (18q21.1). The fifth individual had a proximal breakpoint identical to the other three, but a distal breakpoint at 43.5 Mb (18q21.1). The clinical findings were of interest because the three individuals with the smaller deletions lacked major anomalies. All five individuals were developmentally delayed; however, the discrepancy between their expressive and receptive language abilities was striking, with expressive language being much more severely affected. This leads us to hypothesize that there are genes in this region of chromosome 18 that are specific to the neural and motor planning domains necessary for speech. Additionally, this may represent a previously underappreciated syndrome since these children do not have the typical clinical abnormalities that would lead to a chromosome analysis.
Cody
Jannine D
JD
Department of Pediatrics, University of Texas Health Science Center, San Antonio, Texas 78229, USA. cody@uthscsa.edu
Sebold
Courtney
C
Malik
Amtul
A
Heard
Patricia
P
Carter
Erika
E
Crandall
Analisa
A
Soileau
Bridgette
B
Semrud-Clikeman
Margaret
M
Cody
Catherine M
CM
Hardies
L Jean
LJ
Li
Jinqi
J
Lancaster
Jack
J
Fox
Peter T
PT
Stratton
Robert F
RF
Perry
Brian
B
Hale
Daniel E
DE
D000015:Abnormalities, Multiple / Q000235:genetics*; D000328:Adult; D000886:Anthropometry; D001519:Behavior; D002648:Child; D002675:Child, Preschool; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics*; D003071:Cognition; D005260:Female; D006801:Humans; D007223:Infant; D007805:Language Development Disorders / Q000235:genetics*; D008297:Male; D009483:Neuropsychological Tests; D017384:Sequence Deletion / Q000235:genetics*; D013577:Syndrome