Kwangmi Ahn's research while affiliated with National Institute of Mental Health (NIMH) and other places

Publications (14)

Chapter
Intellectual disability, in its more common mild form and its more severe form, is the consequence of highly interactive genetic and environmental causes. It is an important area for psychiatrists, as comorbidity with psychiatric disorders is frequent. This chapter presents the causes and clinical features of the best characterized syndromes associ...
Article
Background Chromosomal Copy Number Variants (CNVs) associated with schizophrenia also carry etiological risk for neurodevelopmental disorders, including autism and intellectual deficiency. It is not known however what is their risk for any disorders. Here we applied well-replicated ‘neurodevelopmental’ CNVs (NRXN1 del, MYT1L dup, 15q13.3 del/dup, 1...
Article
Adult attention-deficit/hyperactivity disorder (ADHD) was a rare diagnosis 30 years ago, but epidemiological studies in the 2000s estimated a prevalence between 2% and 5%.¹ More recent reports suggest there may be a rapid increase in new diagnoses, much as has been found for childhood ADHD.² Changes to diagnostic criteria in DSM-5 (compared with DS...
Article
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We report two cases of paternally inherited 15q13.3 duplications in carriers diagnosed with childhood-onset schizophrenia (COS), a rare neurodevelopmental disorder of proposed polygenic origin with onset in children before age 13. This study documents that the 15q13.3 deletion and duplication exhibit pathogenicity for COS, with both copy number var...
Article
Objective: Childhood-onset schizophrenia (COS) is a rare but severe form of the disorder, which is often treatment refractory. Short-term studies have indicated a greater differential efficacy, evident through effect sizes, favoring clozapine over other agents in alleviating negative symptoms in COS patients compared with adult-onset patients (AOS...
Article
Full-text available
Childhood-onset schizophrenia (COS), defined by the onset of illness before age 13 years, is a rare severe neurodevelopmental disorder of unknown etiology. Recently, sequencing studies have identified rare, potentially causative de novo variants in sporadic cases of adult-onset schizophrenia and autism. In this study, we performed exome sequencing...
Article
Full-text available
The serotonin receptor 2A gene polymorphism is associated with attentional processes in schizophrenia. However, the specificity of the underlying cognitive constructs affected within this domain requires further elucidation. We carried out the first investigation of whether the TC/CC genotype of the 5-HT2A T102C polymorphism confers impairments in...

Citations

... In the DSM-5, there are a reduced number of symptoms for the diagnosis in adults (five instead of six) and a later age of onset (twelve instead of six) needed to diagnose ADHD. These changes to the DSM-IV aim to address the restrictive diagnostic thresholds (19) and the late onset of some symptoms that may occur in adulthood (20). Recent studies concluded that the switch from DSM-IV to DSM-5 diagnostic threshold resulted in a modest increase and less biased ADHD prevalence rate (4,21). ...
... Deletions involving CHRNA7 are rare but are strongly associated with schizophrenia [72,73]: these patients only have one copy of CHRNA7 and two copies of CHRFAM7A, leading to an altered CHRNA7/CHRFAM7A ratio, whereas 15q13.3 duplication has been linked to childhood-onset schizophrenia [110]. A reduced CHRNA7:CHRFAM7A ratio, due to increased CHRFAM7A and/or reduced CHRNA7 expression, has been reported in the prefrontal cortex of patients with bipolar disorder and schizophrenia [55,59]. ...
... Short-term studies suggest that COS patients compared with adultonset schizophrenia (AOS) show a more robust response to clozapine. Children are more susceptible to akathisia (15%) than adults (3%) (Kasoff et al. 2016). ...
... Despite substantial research efforts to understand neurodevelopment outcomes, we know remarkably little about genetic factors and molecular mechanisms influencing cognitive function in preterm children. Previous genetic studies have discovered hundreds of genetic variants that can predispose children to neurodevelopmental disorders including autism spectrum disorder [24], attention deficit disorder with hyperactivity [25], intellectual disability [26,27], specific language impairment [28], specific learning disorders [29], and childhood onset schizophrenia [30]. Some genetic studies have evaluated genetic risk factors for neurodevelopmental outcomes for preterm children or children with low birth weight [31][32][33][34][35][36]. ...
... The study was approved by the Joint South London and Maudsley and Institute of Psychiatry NHS Research Ethics Committee. The sample in this study overlapped with our previous studies (Kumar et al. 2010;Vyas et al. 2014). ...
... For instance, the 5-hydroxytryptamine 2A (5-HT2A) receptor gene polymorphism is associated with sustained attentional impairment in patients with earlyonset schizophrenia. 41 Moreover, the dopamine β-hydroxylase (DβH) polymorphism may be linked to DβH activity in the Chinese population and may influence some aspects of cognitive function in schizophrenia. 42 Some of these loci have been associated with changes in brain structures. ...
... 6,8,9 One study of structural variations (ie, microduplications and microdeletions) found that the overall frequency of CNVs is higher in COS patients compared with adult-onset patients and to population controls. 6,10,11 In schizophrenia, our group found potentially deleterious de novo single base pair variants and showed that the rate of de novo variants in schizophrenia patients is higher than expected. 12,13 The aim of the current study was to measure the rate of de novo variants and to uncover possibly exclusive COS candidate genes, by analyzing de novo rare variants in sporadic COS trios. ...