Variable behavioural phenotypes of patients with monosomies of 15q26 and a review of 16 cases

Clinical analysis of five CHD2 gene mutations in Chinese children with epilepsy

INTRODUCTION

Increasing evidence reveals critical roles for CHD2 in children with developmental and epileptic encephalopathy.

OBJECTIVES

The aim was to present clinical analysis results of five cases with CHD2 mutations and 157 reported cases with non-copy number variations (non-CNV) of CHD2.

METHODS

This study recruited pediatric epilepsy patients with CHD2 mutations and clinical data from November 2016 to October 2023 in the Linyi People's Hospital, China. Whole-exome and gene panel sequencing were employed to find mutations. The HGMD and PubMed databases were examined for documented cases that had CHD2 mutations.

RESULTS

This study reports five cases with CHD2 mutations: c.3543T > A, c.1850A > G, c.2536C > T, c.4233_4236del, c.3782G > C. Three novel mutations (c.3543T > A, c.1850A > G, c.2536C > T) have never been reported. c.4233_4236del has been reported in three cases, indicating that this locus may be a mutation hotspot. c.3782G > C has been reported in one case. All five patients had seizures before the age of four. Three patients had varying degrees of developmental delay, and four patients had varying degrees of intellectual disability. All of them had controlled seizures after Valproic acid (VPA) monotherapy or VPA in combination with other medications. Furthermore, we reviewed 157 reported cases having non-CNV mutations of CHD2. Most mutations of these cases were de novo. Epilepsy, developmental delay, and intellectual disability were the typical clinical phenotypes. We also found a significant clustering of the mutations near the C-terminus of the CHD2 protein (P < 0.001).

CONCLUSION

This study reports new CHD2 genotypes and analyzes reported CHD2 mutation cases. Given its significance in epileptic encephalopathies, research on the CHD2 gene may provide new insights into epileptogenesis.

Clinical characteristics of and growth hormone treatment effects on short stature with type 1 insulin-like growth factor receptor (IGF1R) gene alteration

Short stature with IGF-1 receptor (IGF1R) gene alteration is known as small-for-gestational-age (SGA) short stature with elevated serum IGF1 levels. Its prevalence and clinical characteristics remain unclear. No adapted treatment is available for short stature related to IGF1R gene alteration in Japan, and genetic testing is not yet widely accessible. We investigated short stature with IGF1R gene alterations and analyzed the clinical data of 13 patients using the results of questionnaires issued to the Japanese Society for Pediatric Endocrinology. Four cases were caused by a deletion of chromosome 15q26.3, and eight were caused by heterozygous pathogenic variants in the IGF1R gene. Cases with deletions showed a more severe degree of growth impairment (-4.5 ± 0.43 SD) than those caused by pathological variants (-2.71 ± 0.15 SD) and were accompanied by neurodevelopmental delay. However, cases caused by pathological variants lacked distinctive features. Only three of the 12 cases demonstrated serum IGF1 values exceeding +2 SD, and the other three had values below 0 SD. Four patients did not meet the criteria for SGA at birth. Six patients received GH therapy for SGA short stature and showed improvement in growth rate without any side effects or elevated serum IGF1 levels during treatment. Elevated IGF1 levels (over +2 SD) after GH treatment should be considered a suspicious finding. Owing to the lack of distinctive features, there was a possibility of undiagnosed cases of this condition. Promoting genetic testing and clinical trials on GH administration for this condition is recommended.

Heterozygous rare variants in NR2F2 cause a recognizable multiple congenital anomaly syndrome with developmental delays

Nuclear receptor subfamily 2 group F member 2 (NR2F2 or COUP-TF2) encodes a transcription factor which is expressed at high levels during mammalian development. Rare heterozygous Mendelian variants in NR2F2 were initially identified in individuals with congenital heart disease (CHD), then subsequently in cohorts of congenital diaphragmatic hernia (CDH) and 46,XX ovotesticular disorders/differences of sexual development (DSD); however, the phenotypic spectrum associated with pathogenic variants in NR2F2 remains poorly characterized. Currently, less than 40 individuals with heterozygous pathogenic variants in NR2F2 have been reported. Here, we review the clinical and molecular details of 17 previously unreported individuals with rare heterozygous NR2F2 variants, the majority of which were de novo. Clinical features were variable, including intrauterine growth restriction (IUGR), CHD, CDH, genital anomalies, DSD, developmental delays, hypotonia, feeding difficulties, failure to thrive, congenital and acquired microcephaly, dysmorphic facial features, renal failure, hearing loss, strabismus, asplenia, and vascular malformations, thus expanding the phenotypic spectrum associated with NR2F2 variants. The variants seen were predicted loss of function, including a nonsense variant inherited from a mildly affected mosaic mother, missense and a large deletion including the NR2F2 gene. Our study presents evidence for rare, heterozygous NR2F2 variants causing a highly variable syndrome of congenital anomalies, commonly associated with heart defects, developmental delays/intellectual disability, dysmorphic features, feeding difficulties, hypotonia, and genital anomalies. Based on the new and previous cases, we provide clinical recommendations for evaluating individuals diagnosed with an NR2F2-associated disorder.

15q26.3 deletions distal to IGF1R cause growth retardation, congenital heart defect and skeletal anomalies: Case report and review of literature

15q26 deletion is a rare genomic disorder characterized by intrauterine and postnatal growth retardation, microcephaly, intellectual disability, and congenital malformations. Here, we report a 4-month-old female with intrauterine growth retardation, short stature, pulmonary hypertension, atrial septal defect and congenital bowing of long bones of the legs. Chromosomal microarray analysis showed a de novo deletion of approximately 2.1 Mb at 15q26.3 region that does not include IGF1R. Our analysis of patients documented in the literature and the DECIPHER database with 15q26 deletions distal to IGF1R, including 10 patients with de novo pure deletions, allowed us to define the smallest region of overlap to 686 kb. This region includes ALDH1A3, LRRK1, CHSY1, SELENOS, SNRPA1, and PCSK6. We propose haploinsufficiency of one or more genes, besides IGF1R, within this region may contribute to the clinical findings in patients with 15q26.3 deletion.

Chromosomal Microarray Analysis in Fetuses Detected with Isolated Cardiovascular Malformation: A Multicenter Study, Systematic Review of the Literature and Meta-Analysis

Cardiovascular malformations (CVM) represent the most common structural anomalies, occurring in 0.7% of live births. The CVM prenatal suspicion should prompt an accurate investigation with fetal echocardiography and the assessment through genetic counseling and testing. In particular, chromosomal microarray analysis (CMA) allows the identification of copy number variations. We performed a systematic review and meta-analysis of the literature, studying the incremental diagnostic yield of CMA in fetal isolated CVM, scoring yields for each category of heart disease, with the aim of guiding genetic counseling and prenatal management. At the same time, we report 59 fetuses with isolated CVM with normal karyotype who underwent CMA. The incremental CMA diagnostic yield in fetuses with isolated CVM was 5.79% (CI 5.54–6.04), with conotruncal malformations showing the higher detection rate (15.93%). The yields for ventricular septal defects and aberrant right subclavian artery were the lowest (2.64% and 0.66%). Other CVM ranged from 4.42% to 6.67%. In the retrospective cohort, the diagnostic yield was consistent with literature data, with an overall CMA diagnostic yield of 3.38%. CMA in the prenatal setting was confirmed as a valuable tool for investigating the causes of fetal cardiovascular malformations.

Clinical Study of 8 Cases of CHD2 Gene Mutation–Related Neurological Diseases and Their Mechanisms

Background: The chromodomain helicase DNA-binding protein 2 (CHD2) gene, is an ATPase and part of the CHD family of chromatin remodelers. Mutations in the CHD2 gene are inherited in an autosomal-dominant manner and can lead to intellectual disability, epilepsy, and autism. We investigated the clinical characteristics of CHD2-related conditions and their possible pathogenesis.

Methods: We collected and analysed the clinical data of patients that were identified as having CHD2 mutations. Genetic testing was performed using targeted sequencing or whole-exome sequencing. We analysed the expression of CHD2 and repressor element 1-silencing transcription factor (REST) in blood samples using quantitative PCR and the conservation of the mutations. The CHD2 mutations we identified were compared with the known mutations reported in the CHD2-related literature.

Results: Eight patients with CHD2 gene mutations were analysed. Six mutations were identified; four were unreported previously (c.670C>T; c.4012A>C; c.2416dup; c.1727–1728insAT), and two were known mutations: c.5035C>T (two cases) and c.4173dup (two cases). Among these mutations, seven were de novo mutations, and one could not be determined because the parents refused genetic testing. The clinical manifestations included mild or severe intellectual disability, epilepsy, and behavioural abnormalities. Quantitative PCR showed that the CHD2 gene expression levels among the patients, parents, and the controls were not significantly different. The levels of REST gene expression in the patients were significantly higher than those of the controls; thus, mutation of the CHD2 gene led to an increase in the expression level of the REST gene. The mutations reported were all located in conserved positions in different species. Among the various medications administered for treatment, valproate showed the best results for the treatment of epilepsy caused by CHD2 gene mutation.

Conclusion: Mutation in CHD2 did not lead to a significant decrease in its expression level, indicating that the clinical phenotype was unrelated to its expression level, and the mutant protein may retain some function. Most of the mutations relatively stable. In addition, the clinical manifestations from the same mutation in the CHD2 gene were different among the known cases; this may be related to the regulation of REST or other regulatory factors.

The phenotype and rhGH treatment response of ring Chromosome 15 Syndrome: Case report and literature review

Background

Ring chromosome 15 [r (15)] is an uncommon finding with various clinical manifestations. A common phenotype for these patients has not been established and data on the efficacy of recombinant human growth hormone (rhGH) treatment in patients with r (15) syndrome are limited.

Methods

One short stature patient in our hospital with r (15) syndrome by whole exome sequencing (WES) and karyotype examination was included. All published r (15) syndrome cases as of March 15, 2021, were searched, and their clinical information was recorded and summarized.

Results

One 11.5‐year‐old female with prenatal and postnatal growth retardation, ventricular septal defect, intellectual disability, downward corners, short fifth metacarpal bone, scattered milk coffee spots, and a right ovarian cyst was included. Her height was 126.9 cm (−3.45 SDS). Karyotype analysis showed 46, XX, r (15). WES revealed a 4.5 Mb heterozygous deletion in the chromosome 15q26.2‐q26.3 region, encompassing genes from ARRDC4 to OR4F15. Gonadotrophin‐releasing hormone analogue (triptorelin) and rhGH were administered for 6 months. The height has increased 3.8 cm (+0.2SDS) and the calculated growth rate has improved from 4.7 to 7.6 cm/y. The literature review indicated the main clinical manifestations of r (15) syndrome with prenatal and postnatal growth retardation, characteristic craniofacial features, and multisystem abnormalities, and rhGH treatment is beneficial for r (15) syndrome patients with short stature.

Conclusion

We delineate the clinical spectrum of r (15) syndrome with the identification of an additional individual and rhGH treatment is beneficial for r (15) syndrome patients with short stature.

15q26 deletion in a patient with congenital heart defect, growth restriction and intellectual disability: case report and literature review

Background

15q26 deletion is a relatively rare chromosomal disorder, and it is described only in few cases. Patients with this aberration show many signs and symptoms, particularly pre- and postnatal growth restriction, developmental delay, microcephaly, intellectual disability and various congenital malformations.

Case presentation

We report on a girl, 4 years old, of consanguineous parents, with a 15q26 deletion. Clinical manifestations included failure to thrive, developmental delay, microcephaly, dysmorphic facies with broad forehead, hypertelorism, narrowed eyelid slits and protruding columella. The patient also showed skeletal abnormalities, especially clinodactyly of the 5th finger, varus equine right foot and left club foot. Additionally, she had teething delay and divergent strabismus. Heart ultrasound displayed two atrial septal defects with left-to-right shunt, enlarging the right cavities. Routine cytogenetic analysis revealed a shortened 15q chromosome. Subsequent array analysis disclosed a terminal 9.15 Mb deletion at subband 15q26.1-q26.3. Four candidate genes associated with 15q26 deletion phenotype were within the deleted region, i.e. IGF1R, NR2F2, CHD2 and MEF2A.

Conclusion

We report on an additional case of 15q26 monosomy, characterized by array-CGH. Molecular cytogenetic analysis allowed us to identify the exact size of the deletion, and four candidate genes for genotype-phenotype correlation. 15q26 monosomy should be considered when growth retardation is associated with hearing anomalies and congenital heart defect, especially atrioventricular septal defects (AVSDs) and/or aortic arch anomaly (AAA).

Spread of X-chromosome inactivation into autosomal regions in patients with unbalanced X-autosome translocations and its phenotypic effects

Patients with unbalanced X-autosome translocations are rare and usually present a skewed X-chromosome inactivation (XCI) pattern, with the derivative chromosome being preferentially inactivated, and with a possible spread of XCI into the autosomal regions attached to it, which can inactivate autosomal genes and affect the patients' phenotype. We describe three patients carrying different unbalanced X-autosome translocations, confirmed by G-banding karyotype and array techniques. We analyzed their XCI pattern and inactivation spread into autosomal regions, through HUMARA, ZDHHC15 gene assay and the novel 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, and identified an extremely skewed XCI pattern toward the derivative chromosomes for all the patients, and a variable pattern of late-replication on the autosomal regions of the derivative chromosomes. All patients showed phenotypical overlap with patients presenting deletions of the autosomal late-replicating regions, suggesting that the inactivation of autosomal segments may be responsible for their phenotype. Our data highlight the importance of the XCI spread into autosomal regions for establishing the clinical picture in patients carrying unbalanced X-autosome translocations, and the incorporation of EdU as a novel and precise tool to evaluate the inactivation status in such patients.

CHD2-Related CNS Pathologies

Epileptic encephalopathies (EE) are severe epilepsy syndromes characterized by multiple seizure types, developmental delay and even regression. This class of disorders are increasingly being identified as resulting from de novo genetic mutations including many identified mutations in the family of chromodomain helicase DNA binding (CHD) proteins. In particular, several de novo pathogenic mutations have been identified in the gene encoding chromodomain helicase DNA binding protein 2 (CHD2), a member of the sucrose nonfermenting (SNF-2) protein family of epigenetic regulators. These mutations in the CHD2 gene are causative of early onset epileptic encephalopathy, abnormal brain function, and intellectual disability. Our understanding of the mechanisms by which modification or loss of CHD2 cause this condition remains poorly understood. Here, we review what is known and still to be elucidated as regards the structure and function of CHD2 and how its dysregulation leads to a highly variable range of phenotypic presentations.

Case of 15q26-qter deletion associated with a Prader-Willi phenotype

Prader-Willi syndrome (PWS) is one of the common neurogenetic disorders associated with intellectual disability. PWS involves a complex inheritance pattern and is caused by an absence of gene expression on the paternally inherited 15q11.2-q13 region, either due to deletion, maternal uniparental disomy or imprinting defect. The syndrome is characterized principally by severe neonatal hypotonia, a weak suck in infancy that is later followed by hyperphagia and obesity, developmental delay, intellectual disability and short stature. In the case of the chromosome 15q26-qter deletion syndrome or Drayer's syndrome, very few reports have been published. Its characteristics include intrauterine growth restriction, postnatal growth failure, varying degrees of intellectual disability, developmental delay, typical facial appearance and diaphragmatic hernia. The present paper describes a female patient in whom clinical findings were suggestive of PWS and deletion in the 15q26-qter region. Both karyotyping and methylation-specific polymerase chain reaction were shown to be normal. Nevertheless, fluorescence in situ hybridization showed a 15qter deletion that was later mapped by single nucleotide polymorphism (SNP)-array. The deleted genomic region involves the insulin-like growth factor-1 receptor (IGF1R) gene, which is related to short stature, developmental delay and intellectual disability. This case had various clinical characteristics in common with the cases of 15q26-qter deletionand characteristics compatible with PWS.

Synemin-related skeletal and cardiac myopathies: an overview of pathogenic variants

This review analyzes data concerning patients with cardiomyopathies or skeletal myopathies associated with a variation in the intermediate filament (IF) synemin gene (SYNM), also referred to as desmuslin (DMN). Molecular studies demonstrate that synemin copolymerizes with desmin and vimentin IF and interacts with vinculin, α-actinin, α-dystrobrevin, dystrophin, talin, and zyxin. It has been found that synemin is an A-kinase-anchoring protein (AKAP) that anchors protein kinase A (PKA) and modulates the PKA-dependent phosphorylation of several cytoskeletal substrates such as desmin. Because several IF proteins, including desmin, have been implicated in human genetic disorders such as dominant or recessive congenital and adult-onset myopathy, synemin becomes a significant candidate for cardiac and skeletal myopathies of unknown etiology. Because SYNM is a new candidate gene that displays numerous sequence polymorphisms, in this review, we summarize the genetic and clinical literature about SYNM mutations. Protein-changing variants (missense, frameshifts, nonsense) were further evaluated based on structural modifications and amino acid interactions. We present in silico modeling of helical salt-bridges between residues to evaluate the impact of the synemin networks crucial to interactions with cytoskeletal proteins. Finally, a discussion is featured regarding certain variants that may contribute to the disease state.

[Genetic analysis of a fetus with multiple malformations caused by complex translocations of four chromosomes]

OBJECTIVE

To conduct genetic analysis in a fetus with complex translocation of four chromosomes.

METHODS

G-banded chromosome karyotype analysis, single nucleotide polymorphism array (SNP array) and fluorescence in situ hybridization (FISH) were performed in a fetus with multiple malformations. Peripheral blood chromosome karyotype and FISH were also carried out for the parents.

RESULTS

The fetal amniotic fluid karyotype was 46, XY, t(12; 13)(q22; q32). SNP array analysis showed that there were 20 192 kb duplication at 1q42.13q44 and 13 293 kb deletion at 15q26.1q26.3 in the fetus. The results of karyotype and SNP array were inconsistent. FISH analyses on the parental peripheral blood samples demonstrated that the mother was a cryptic 46, XX, t(1; 15)(q42.1; q26.1) translocation. The fetus had inherited 46, XY, t(12; 13)(q22; q32) from his father and der(15)t(1; 15)(q42.1; q26.1) from his mother.

CONCLUSIONS

The 1q42.13q44 duplication and 15q26.1q26.3 deletion may have contributed to the abnormal sonographic features of the fetus. The combination of cytogenetic, SNP array and FISH techniques was beneficial for providing an accurate genetic counseling.

Recurrent Copy Number Variants Associated with Syndromic Short Stature of Unknown Cause

BACKGROUND/AIMS

Genetic imbalances are responsible for many cases of short stature of unknown etiology. This study aims to identify recurrent pathogenic copy number variants (CNVs) in patients with syndromic short stature of unknown cause.

METHODS

We selected 229 children with short stature and dysmorphic features, developmental delay, and/or intellectual disability, but without a recognized syndrome. All patients were evaluated by chromosomal microarray (array-based comparative genomic hybridization/single nucleotide polymorphism array). Additionally, we searched databases and previous studies to recover recurrent pathogenic CNVs associated with short stature.

RESULTS

We identified 32 pathogenic/probably pathogenic CNVs in 229 patients. By reviewing the literature, we selected 4 previous studies which evaluated CNVs in cohorts of patients with short stature. Taken together, there were 671 patients with short stature of unknown cause evaluated by chromosomal microarray. Pathogenic/probably pathogenic CNVs were identified in 87 patients (13%). Seven recurrent CNVs, 22q11.21, 15q26, 1p36.33, Xp22.33, 17p13.3, 1q21.1, 2q24.2, were observed. They are responsible for about 40% of all pathogenic/probably pathogenic genomic imbalances found in short stature patients of unknown cause.

CONCLUSION

CNVs seem to play a significant role in patients with short stature. Chromosomal microarray should be used as a diagnostic tool for evaluation of growth disorders, especially for syndromic short stature of unknown cause.

Use of clinical chromosomal microarray in Chinese patients with autism spectrum disorder-implications of a copy number variation involving DPP10

Background

Array comparative genomic hybridization (aCGH) is recommended as a first-tier genetic test for children with autism spectrum disorder (ASD). However, interpretation of results can often be challenging partly due to the fact that copy number variants (CNVs) in non-European ASD patients are not well studied. To address this literature gap, we report the CNV findings in a cohort of Chinese children with ASD.

Methods

DNA samples were obtained from 258 Chinese ASD patients recruited from a child assessment center between January 2011 and August 2014. aCGH was performed using NimbleGen-CGX-135k or Agilent-CGX 60k oligonucleotide array. Results were classified based on existing guidelines and literature.

Results

Ten pathogenic CNVs and one likely pathogenic CNV were found in nine patients, with an overall diagnostic yield of 3.5%. A 138 kb duplication involving 3′ exons of DPP10 (arr[GRCh37] 2q14.1(116534689_116672358)x3), reported to be associated with ASD, was identified in one patient (0.39%). The same CNV was reported as variant of uncertain significance (VUS) in DECIPHER database. Multiple individuals of typical development carrying a similar duplication were identified among our ancestry-matched control with a frequency of 6/653 (0.92%) as well as from literature and genomic databases.

Conclusions

The DPP10 duplication is likely a benign CNV polymorphism enriched in Southern Chinese with a population frequency of ~1%. This highlights the importance of using ancestry-matched controls in interpretation of aCGH findings.

Electronic supplementary material

The online version of this article (doi:10.1186/s13229-017-0136-x) contains supplementary material, which is available to authorized users.

Expanding the clinical spectrum of chromosome 15q26 terminal deletions associated with IGF-1 resistance

Haploinsufficiency of the insulin-like growth factor-1 receptor (IGF1R) gene on chromosome 15q26.3 is associated with impaired prenatal and postnatal growth, developmental delay, dysmorphic features and skeletal abnormalities. Terminal deletions of chromosome 15q26 arising more proximally may also be associated with congenital heart disease, epilepsy, diaphragmatic hernia and renal anomalies. We report three additional cases of 15q26 terminal deletions with novel features which may further expand the spectrum of this rarely reported contiguous gene syndrome. Phenotypic features including neonatal lymphedema, aplasia cutis congenita and aortic root dilatation have not been reported previously. Similarly, laboratory features of insulin-like growth factor 1 (IGF-1) resistance are described, including markedly elevated IGF-1 of up to +4.7 SDS. In one patient, the elevated IGF-1 declined over time and this coincided with a period of spontaneous growth acceleration.

CONCLUSION

Deletions of 15q26 are a potential risk factor for aortic root dilatation, neonatal lymphedema and aplasia cutis in addition to causing growth restriction. What is Known: • Terminal deletions of chromosome 15q26 are associated with impaired prenatal and postnatal growth, developmental delay, dysmorphic features and skeletal abnormalities. What is New: • Neonatal lymphedema, aplasia cutis congenita and aortic root dilatation have not been previously described in 15q26 terminal deletions and may represent novel features. • IGF-1 levels may be increased up to 4.7 SDS.

An update on the comorbidity of ADHD and ASD: a focus on clinical management

Attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) commonly co-occur. With the DSM-5, clinicians are permitted to make an ASD diagnosis in the context of ADHD. In earlier versions of the DSM, this was not acceptable. Both ASD and ADHD are reported to have had substantial increases in prevalence within the past 10 years. As a function of both the increased prevalence of both disorders as well as the ability to make an ASD diagnosis in ADHD, there has been a significant amount of research focusing on the comorbidity between ADHD and ASD in the past few years. Here, we provide an update on the biological, cognitive and behavioral overlap/distinctiveness between the two neurodevelopmental disorders with a focus on data published in the last four years. Treatment strategies for the comorbid condition as well as future areas of research and clinical need are discussed.

A rare de novo interstitial duplication of 15q15.3q21.2 in a boy with severe short stature, hypogonadism, global developmental delay and intellectual disability

BACKGROUND

Interstitial duplications distal to 15q13 are very rare.

CASE PRESENTATION

Here, we reported a 14-year-old boy with severe short stature, delayed bone age, hypogonadism, global developmental delay and intellectual disability. His had distinctive facial features including macrocephaly, broad forehead, deep-set and widely spaced eyes, broad nose bridge, shallow philtrum and thick lips. A de novo 6.4 Mb interstitial duplication of 15q15.3q21.2 was detected by chromosomal microarray analysis. We compared our patient's clinical phenotypes with those of several individuals with overlapping duplications and several candidate genes responsible for the phenotypes were identified as well.

CONCLUSION

The results suggest a novel contiguous gene duplication syndrome characterized with shared features including short stature, hypogonadism, global developmental delay and other congenital anomalies.

Recombinant Human Growth Hormone Therapy in Children with Chromosome 15q26 Deletion

BACKGROUND

The insulin-like growth factor 1 receptor (IGF IR) gene is located on chromosome 15q26.3. Heterozygous 15q26 deletions involving the IGFIR gene are rare, resulting in intrauterine and postnatal growth retardation, developmental delay and microcephaly. Limited evidence exists on the effect of growth hormone (GH) therapy in these cases.

METHODS

We report a series of cases with 15q26 deletions, including response to GH treatment.

RESULTS

Seven children (2 males) presented with short stature [median height standard deviation score (SDS) of -4.8 (range -3.0 to -5.6)]. GH was started at a median age of 5 years (range 1.8 to 12.4) for a median duration of 5.8 years (range 1.0 to 12.4). Median height SDS increased by +0.6 (range 0.1 to 1.0), +1.3 (range 0.1 to 2.4) and +1.4 (range 0.8 to 3.3) after 1 (n = 7), 5 (n = 4) and 10 years (n = 3) of GH treatment, respectively. Four patients reached final height after 5.8 to 12.4 years of GH with a median change in height SDS of +1.1 (range 0 to 3.3).

CONCLUSION

This study demonstrates a moderate, though variable, response to GH therapy, suggesting that GH resistance caused by heterozygous IGFIR deletions can be partially overcome by GH therapy. The first-year response was moderate, and whilst long-term treatment improved height SDS, the final adult height remained reduced. Therefore, an individual trial of GH therapy may be appropriate in these patients. © 2015 S. Karger AG, Basel.

Genetic diagnosis of autism spectrum disorders: the opportunity and challenge in the genomics era

A genetic etiology for autism spectrum disorders (ASDs) was first suggested from twin studies reported in the 1970s. The identification of gene mutations in syndromic ASDs provided evidence to support a genetic cause of ASDs. More recently, genome-wide copy number variant and sequence analyses have uncovered a list of rare and highly penetrant copy number variants (CNVs) or single nucleotide variants (SNVs) associated with ASDs, which has strengthened the claim of a genetic etiology for ASDs. Findings from research studies in the genetics of ASD now support an important role for molecular diagnostics in the clinical genetics evaluation of ASDs. Various molecular diagnostic assays including single gene tests, targeted multiple gene panels and copy number analysis should all be considered in the clinical genetics evaluation of ASDs. Whole exome sequencing could also be considered in selected clinical cases. However, the challenge that remains is to determine the causal role of genetic variants identified through molecular testing. Variable expressivity, pleiotropic effects and incomplete penetrance associated with CNVs and SNVs also present significant challenges for genetic counseling and prenatal diagnosis.