ARRAY-BASED COMPARATIVE GENOMIC HYBRIDIZATION
ANALYSIS IN CHILDREN WITH DEVELOPMENTAL
DELAY/INTELLECTUAL DISABILITY Türkyılmaz A, Geckinli BB, Tekin E, Ates EA, Yarali O, Cebi AH, Arman A *Corresponding Author: Ayberk Türkyılmaz, M.D., Assistant Professor, Department of Medical Genetics,
Karadeniz Technical University Faculty of Medicine, Farabi Street, 61080 Ortahisar, Trabzon,
Turkey. Tel: +90-505-812-03-34. Fax: +90-462-377-51-06. E-mail: ayberkturkyilmaz@gmail.com page: 15
|
INTRODUCTION
Developmental delay (DD) is a condition wherein
developmental milestones and learning skills do not occur
at the expected age range for patients under 5 years of age.
Areas used for evaluating developmental stages are gross
and fine motor skills, speech and language skills, cognition,
and personal-social development. Intellectual disability
(ID) is characterized by limited or insufficient development
of mental abilities, including intellectual functioning
impairments, such as learning and cause-effect relationship
[1]. Intellectual disability cases are often diagnosed in the
early school-age period. The incidence of DD is 1.0-3.0%
in the general population, whereas that of ID is approximately
2.7% among early school-age children [2]. Some
cases have DD or ID as the only finding and are called
isolated cases. Conversely, cases accompanied by facial
dysmorphism, autism spectrum disorder (ASD), epilepsy
and congenital anomalies, are called syndromic DD/ID [3].
Recent studies have shown that biological signaling pathways
causing DD/ID, ASD, and epilepsy phenotypes are
common. Additionally, the relationship between signaling
pathways involved in early brain development, synaptic
plasticity, and neuronal migration and the formation of
these phenotypes has been demonstrated [4].
Isolated and syndromic DD/ID cases show extreme
genetic heterogeneity. Genetic etiology can be detected in
approximately 40.0% of the cases, whereas chromosomal
abnormalities are observed in 25.0% [5,6]. Conventional
cytogenetic testing can be used for detecting >5 Mb chromosome abnormalities. Moreover, specific chromosomal
abnormalities can be investigated using fluorescence in situ
hybridization (FISH) techniques. The diagnostic yield of
both techniques for detecting DD/ID cases is approximately
5.0-6.0% [7]. Array-based comparative genomic hybridization
(aCGH) can detect copy number variations (CNVs) in
the whole genome at higher resolution than conventional
cytogenetic methods. Copy number variations are defined as
changes >1 kb resulting in an increase and/or decrease in the
genomic DNA [8]. The CNVs are divided into two groups:
recurrent and non recurrent. Recurrent CNVs often arise
during meiosis from non-allelic homologous recombination
(NAHR) between low copy repeat elements (LCRs). Non
recurrent novel microdele-tion/microduplication syndromes
have been identified in recent years owing to the widespread
application of aCGH in diagnosis [9,10]. In a review published
by Miller et al. [11] in 2010, the diagnostic yield of
aCGH was 12.2% in 21,698 DD/ID cases retrieved from 33
different studies. The aCGH is currently recommended as
the first-tier genetic test for DD/ID cases worldwide [11].
The aim of this study was to discuss the clinical findings
and aCGH analysis results of isolated and syndromic DD/
ID cases in the context of genotype-phenotype correlation.
|
|
|
|
|
Number 26 Number 26 VOL. 26(2), 2023 All in one |
Number 26 VOL. 26(2), 2023 |
Number 26 VOL. 26, 2023 Supplement |
Number 26 VOL. 26(1), 2023 |
Number 25 VOL. 25(2), 2022 |
Number 25 VOL. 25 (1), 2022 |
Number 24 VOL. 24(2), 2021 |
Number 24 VOL. 24(1), 2021 |
Number 23 VOL. 23(2), 2020 |
Number 22 VOL. 22(2), 2019 |
Number 22 VOL. 22(1), 2019 |
Number 22 VOL. 22, 2019 Supplement |
Number 21 VOL. 21(2), 2018 |
Number 21 VOL. 21 (1), 2018 |
Number 21 VOL. 21, 2018 Supplement |
Number 20 VOL. 20 (2), 2017 |
Number 20 VOL. 20 (1), 2017 |
Number 19 VOL. 19 (2), 2016 |
Number 19 VOL. 19 (1), 2016 |
Number 18 VOL. 18 (2), 2015 |
Number 18 VOL. 18 (1), 2015 |
Number 17 VOL. 17 (2), 2014 |
Number 17 VOL. 17 (1), 2014 |
Number 16 VOL. 16 (2), 2013 |
Number 16 VOL. 16 (1), 2013 |
Number 15 VOL. 15 (2), 2012 |
Number 15 VOL. 15, 2012 Supplement |
Number 15 Vol. 15 (1), 2012 |
Number 14 14 - Vol. 14 (2), 2011 |
Number 14 The 9th Balkan Congress of Medical Genetics |
Number 14 14 - Vol. 14 (1), 2011 |
Number 13 Vol. 13 (2), 2010 |
Number 13 Vol.13 (1), 2010 |
Number 12 Vol.12 (2), 2009 |
Number 12 Vol.12 (1), 2009 |
Number 11 Vol.11 (2),2008 |
Number 11 Vol.11 (1),2008 |
Number 10 Vol.10 (2), 2007 |
Number 10 10 (1),2007 |
Number 9 1&2, 2006 |
Number 9 3&4, 2006 |
Number 8 1&2, 2005 |
Number 8 3&4, 2004 |
Number 7 1&2, 2004 |
Number 6 3&4, 2003 |
Number 6 1&2, 2003 |
Number 5 3&4, 2002 |
Number 5 1&2, 2002 |
Number 4 Vol.3 (4), 2000 |
Number 4 Vol.2 (4), 1999 |
Number 4 Vol.1 (4), 1998 |
Number 4 3&4, 2001 |
Number 4 1&2, 2001 |
Number 3 Vol.3 (3), 2000 |
Number 3 Vol.2 (3), 1999 |
Number 3 Vol.1 (3), 1998 |
Number 2 Vol.3(2), 2000 |
Number 2 Vol.1 (2), 1998 |
Number 2 Vol.2 (2), 1999 |
Number 1 Vol.3 (1), 2000 |
Number 1 Vol.2 (1), 1999 |
Number 1 Vol.1 (1), 1998 |
|
|