Profiling PI3K-AKT-MTOR variants in focal brain malformations reveals new insights for diagnostic care.

Focal malformations of cortical development including focal cortical dysplasia, hemimegalencephaly and megalencephaly, are a spectrum of neurodevelopmental disorders associated with brain overgrowth, cellular and architectural dysplasia, intractable epilepsy, autism and intellectual disability. Importantly, focal cortical dysplasia is the most common cause of focal intractable paediatric epilepsy. Gain and loss of function variants in the PI3K-AKT-MTOR pathway have been identified in this spectrum, with variable levels of mosaicism and tissue distribution. In this study, we performed deep molecular profiling of common PI3K-AKT-MTOR pathway variants in surgically resected tissues using droplet digital polymerase chain reaction (ddPCR), combined with analysis of key phenotype data. A total of 159 samples, including 124 brain tissue samples, were collected from 58 children with focal malformations of cortical development. We designed an ultra-sensitive and highly targeted molecular diagnostic panel using ddPCR for six mutational hotspots in three PI3K-AKT-MTOR pathway genes, namely PIK3CA (p.E542K, p.E545K, p.H1047R), AKT3 (p.E17K) and MTOR (p.S2215F, p.S2215Y). We quantified the level of mosaicism across all samples and correlated genotypes with key clinical, neuroimaging and histopathological data. Pathogenic variants were identified in 17 individuals, with an overall molecular solve rate of 29.31%. Variant allele fractions ranged from 0.14 to 22.67% across all mutation-positive samples. Our data show that pathogenic MTOR variants are mostly associated with focal cortical dysplasia, whereas pathogenic PIK3CA variants are more frequent in hemimegalencephaly. Further, the presence of one of these hotspot mutations correlated with earlier onset of epilepsy. However, levels of mosaicism did not correlate with the severity of the cortical malformation by neuroimaging or histopathology. Importantly, we could not identify these mutational hotspots in other types of surgically resected epileptic lesions (e.g. polymicrogyria or mesial temporal sclerosis) suggesting that PI3K-AKT-MTOR mutations are specifically causal in the focal cortical dysplasia-hemimegalencephaly spectrum. Finally, our data suggest that ultra-sensitive molecular profiling of the most common PI3K-AKT-MTOR mutations by targeted sequencing droplet digital polymerase chain reaction is an effective molecular approach for these disorders with a good diagnostic yield when paired with neuroimaging and histopathology.

Tracking the motion of the KV1.2 voltage sensor reveals the molecular perturbations caused by a de novo mutation in a case of epilepsy.

KEY POINTS: KV1.2 channels, encoded by the KCNA2 gene, regulate neuronal excitability by conducting K+ upon depolarization. A new KCNA2 missense variant was discovered in a patient with epilepsy, causing amino acid substitution F302L at helix S4, in the KV1.2 voltage-sensing domain. Immunocytochemistry and flow cytometry showed that F302L does not impair KCNA2 subunit surface trafficking. Molecular dynamics simulations indicated that F302L alters the exposure of S4 residues to membrane lipids. Voltage clamp fluorometry revealed that the voltage-sensing domain of KV1.2-F302L channels is more sensitive to depolarization. Accordingly, KV1.2-F302L channels opened faster and at more negative potentials; however, they also exhibited enhanced inactivation: that is, F302L causes both gain- and loss-of-function effects. Coexpression of KCNA2-WT and -F302L did not fully rescue these effects. The proband's symptoms are more characteristic of patients with loss of KCNA2 function. Enhanced KV1.2 inactivation could lead to increased synaptic release in excitatory neurons, steering neuronal circuits towards epilepsy. ABSTRACT: An exome-based diagnostic panel in an infant with epilepsy revealed a previously unreported de novo missense variant in KCNA2, which encodes voltage-gated K+ channel KV1.2. This variant causes substitution F302L, in helix S4 of the KV1.2 voltage-sensing domain (VSD). F302L does not affect KCNA2 subunit membrane trafficking. However, it does alter channel functional properties, accelerating channel opening at more hyperpolarized membrane potentials, indicating gain of function. F302L also caused loss of KV1.2 function via accelerated inactivation onset, decelerated recovery and shifted inactivation voltage dependence to more negative potentials. These effects, which are not fully rescued by coexpression of wild-type and mutant KCNA2 subunits, probably result from the enhancement of VSD function, as demonstrated by optically tracking VSD depolarization-evoked conformational rearrangements. In turn, molecular dynamics simulations suggest altered VSD exposure to membrane lipids. Compared to other encephalopathy patients with KCNA2 mutations, the proband exhibits mild neurological impairment, more characteristic of patients with KCNA2 loss of function. Based on this information, we propose a mechanism of epileptogenesis based on enhanced KV1.2 inactivation leading to increased synaptic release preferentially in excitatory neurons, and hence the perturbation of the excitatory/inhibitory balance of neuronal circuits.

Nonreentrant atrial tachycardia occurs independently of hypertrophic cardiomyopathy in RASopathy patients.

Multifocal atrial tachycardia (MAT) has a well-known association with Costello syndrome, but is rarely described with related RAS/MAPK pathway disorders (RASopathies). We report 11 patients with RASopathies (Costello, Noonan, and Noonan syndrome with multiple lentigines [formerly LEOPARD syndrome]) and nonreentrant atrial tachycardias (MAT and ectopic atrial tachycardia) demonstrating overlap in cardiac arrhythmia phenotype. Similar overlap is seen in RASopathies with respect to skeletal, musculoskeletal and cutaneous abnormalities, dysmorphic facial features, and neurodevelopmental deficits. Nonreentrant atrial tachycardias may cause cardiac compromise if sinus rhythm is not restored expeditiously. Typical first-line supraventricular tachycardia anti-arrhythmics (propranolol and digoxin) were generally not effective in restoring or maintaining sinus rhythm in this cohort, while flecainide or amiodarone alone or in concert with propranolol were effective anti-arrhythmic agents for acute and chronic use. Atrial tachycardia resolved in all patients. However, a 4-month-old boy from the cohort was found asystolic (with concurrent cellulitis) and a second patient underwent cardiac transplant for heart failure complicated by recalcitrant atrial arrhythmia. While propranolol alone frequently failed to convert or maintain sinus rhythm, fleccainide or amiodarone, occasionally in combination with propranolol, was effective for RASopathy patient treatment for nonreentrant atrial arrhythmia. Our analysis shows that RASopathy patients may have nonreentrant atrial tachycardia with and without associated cardiac hypertrophy. While nonreentrant arrhythmia has been traditionally associated with Costello syndrome, this work provides an expanded view of RASopathy cardiac arrhythmia phenotype as we demonstrate mutant proteins throughout this signaling pathway can also give rise to ectopic and/or MAT.

Further delineation of an entity caused by CREBBP and EP300 mutations but not resembling Rubinstein-Taybi syndrome.

In 2016, we described that missense variants in parts of exons 30 and 31 of CREBBP can cause a phenotype that differs from Rubinstein-Taybi syndrome (RSTS). Here we report on another 11 patients with variants in this region of CREBBP (between bp 5,128 and 5,614) and two with variants in the homologous region of EP300. None of the patients show characteristics typical for RSTS. The variants were detected by exome sequencing using a panel for intellectual disability in all but one individual, in whom Sanger sequencing was performed upon clinical recognition of the entity. The main characteristics of the patients are developmental delay (90%), autistic behavior (65%), short stature (42%), and microcephaly (43%). Medical problems include feeding problems (75%), vision (50%), and hearing (54%) impairments, recurrent upper airway infections (42%), and epilepsy (21%). Major malformations are less common except for cryptorchidism (46% of males), and cerebral anomalies (70%). Individuals with variants between bp 5,595 and 5,614 of CREBBP show a specific phenotype (ptosis, telecanthi, short and upslanted palpebral fissures, depressed nasal ridge, short nose, anteverted nares, short columella, and long philtrum). 3D face shape demonstrated resemblance to individuals with a duplication of 16p13.3 (the region that includes CREBBP), possibly indicating a gain of function. The other affected individuals show a less specific phenotype. We conclude that there is now more firm evidence that variants in these specific regions of CREBBP and EP300 result in a phenotype that differs from RSTS, and that this phenotype may be heterogeneous.

Immune and Genetic Features of the Chromosome 22q11.2 Deletion (DiGeorge Syndrome).

PURPOSE OF REVIEW: This review provides an update on the progress in identifying the range of immunological dysfunction seen in DiGeorge syndrome and on more recent diagnostic and treatment approaches. RECENT FINDINGS: Clinically, the associated thymic hypoplasia/aplasia is well known and can have profound effects on T cell function. Further, the humoral arm of the immune system can be affected, with hypogammaglobulinemia and poor vaccine-specific antibody response. Additionally, genetic testing utilizing chromosomal microarray demonstrates a small but significant number of 22q11 deletions that are not detectable by standard FISH testing. The recent addition of a TREC assay to newborn screening can identify a subset of infants whose severe immune defects may result from 22q11 deletion. This initial presentation now also places the immunologist in the role of "first responder" with regard to diagnosis and management of these patients. DiGeorge syndrome reflects a clinical phenotype now recognized by its underlying genetic diagnosis, chromosome 22q11.2 deletion syndrome, which is associated with multisystem involvement and variable immune defects among patients. Updated genetic and molecular techniques now allow for earlier identification of immune defects and confirmatory diagnoses, in this disorder with life-long clinical issues.

Inherited germline ATRX mutation in two brothers with ATR-X syndrome and osteosarcoma.

We report a family in which two brothers had an undiagnosed genetic disorder comprised of dysmorphic features, microcephaly, severe intellectual disability (non-verbal), mild anemia, and cryptorchidism. Both developed osteosarcoma. Trio exome sequencing (using blood samples from the younger brother and both parents) was performed and a nonsense NM_000489.4:c.7156C>T (p.Arg2386*) mutation in the ATRX gene was identified in the proband (hemizygous) and in the mother's peripheral blood DNA (heterozygous). The mother is healthy, does not exhibit any clinical manifestations of ATR-X syndrome and there was no family history of cancer. The same hemizygous pathogenic variant was confirmed in the affected older brother's skin tissue by subsequent Sanger sequencing. Chromosomal microarray studies of both brothers' osteosarcomas revealed complex copy number alterations consistent with the clinical diagnosis of osteosarcoma. Recently, somatic mutations in the ATRX gene have been observed as recurrent alterations in both osteosarcoma and brain tumors. However, it is unclear if there is any association between osteosarcoma and germline ATRX mutations, specifically in patients with constitutional ATR-X syndrome. This is the first report of osteosarcoma diagnosed in two males with ATR-X syndrome, suggesting a potential increased risk for cancer in patients with this disorder.

Intragenic KANSL1 mutations and chromosome 17q21.31 deletions: broadening the clinical spectrum and genotype-phenotype correlations in a large cohort of patients.

BACKGROUND: The 17q21.31 deletion syndrome phenotype can be caused by either chromosome deletions or point mutations in the KANSL1 gene. To date, about 60 subjects with chromosome deletion and 4 subjects with point mutation in KANSL1 have been reported. Prevalence of chromosome deletions compared with point mutations, genotype-phenotype correlations and phenotypic variability have yet to be fully clarified. METHODS: We report genotype-phenotype correlations in 27 novel subjects with 17q21.31 deletion and in 5 subjects with KANSL1 point mutation, 3 of whom were not previously reported. RESULTS: The prevalence of chromosome deletion and KANSL1 mutation was 83% and 17%, respectively. All patients had similar clinical features, with the exception of macrocephaly, which was detected in 24% of patients with the deletion and 60% of those with the point mutation, and congenital heart disease, which was limited to 35% of patients with the deletion. A remarkable phenotypic variability was observed in both categories, mainly with respect to the severity of ID. Cognitive function was within normal parameters in one patient in each group. Craniosynostosis, subependymal heterotopia and optic nerve hypoplasia represent new component manifestations. CONCLUSIONS: In KANSL1 haploinsufficiency syndrome, chromosome deletions are greatly prevalent compared with KANSL1 mutations. The latter are sufficient in causing the full clinical phenotype. The degree of intellectual disability (ID) appears to be milder than expected in a considerable number of subjects with either chromosome deletion or KANSL1 mutation. Striking clinical criteria for enrolling patients into KANSL1 analysis include speech delay, distinctive facial dysmorphism, macrocephaly and friendly behaviour.

From microscopes to microarrays: dissecting recurrent chromosomal rearrangements.

Submicroscopic chromosomal rearrangements that lead to copy-number changes have been shown to underlie distinctive and recognizable clinical phenotypes. The sensitivity to detect copy-number variation has escalated with the advent of array comparative genomic hybridization (CGH), including BAC and oligonucleotide-based platforms. Coupled with improved assemblies and annotation of genome sequence data, these technologies are facilitating the identification of new syndromes that are associated with submicroscopic genomic changes. Their characterization reveals the role of genome architecture in the aetiology of many clinical disorders. We review a group of genomic disorders that are mediated by segmental duplications, emphasizing the impact that high-throughput detection methods and the availability of the human genome sequence have had on their dissection and diagnosis.

Duplication 12p and Pallister-Killian syndrome: a case report and review of the literature toward defining a Pallister-Killian syndrome minimal critical region.

Pallister-Killian syndrome (PKS) is a multisystem sporadic genetic condition characterized by facial anomalies, variable developmental delay and intellectual impairment, hypotonia, hearing loss, seizures, pigmentary skin differences, temporal alopecia, diaphragmatic hernia, congenital heart defects, and other systemic abnormalities. PKS is typically caused by the presence of a supernumerary isochromosome composed of the short arms of chromosome 12 resulting in tetrasomy 12p, which is often present in a tissue limited mosaic state. The PKS phenotype has also often been observed in individuals with complete or partial duplications of 12p (trisomy 12p rather than tetrasomy 12p) as the result of an interstitial duplication or unbalanced translocation. We have identified a proposita with PKS who has two small de novo interstitial duplications of 12p which, along with a review of previously reported cases, has allowed us to define a minimum critical region for PKS.

Evaluating Genetic Disorders in the Neonate: The Role of Exome Sequencing in the NICU.

With recent advances in the technologies used for genetic diagnosis as well as our understanding of the genetic basis of disease, a growing list of options is available for providers when caring for a newborn with features suggesting an underlying genetic etiology. The choice of the most appropriate genetic test for a specific situation includes clinical considerations such as the phenotypic features and type of genetic abnormality suspected, as well as practical considerations such as cost and turnaround time. In this review, we discuss clinical exome sequencing in the context of genetic evaluation of newborns, including technical considerations, variant interpretation, and incidental/secondary findings. Strengths and limitations of exome sequencing are discussed and compared with those of other commonly known tests such as karyotype analysis, fluorescence in situ hybridization, chromosomal microarray, and sequencing panels, along with integration of results from prenatal testing if available. We also review future directions including genome sequencing and other emerging technologies that are starting to be used in clinical settings.

High-Resolution genomic arrays identify CNVs that phenocopy the chromosome 22q11.2 deletion syndrome.

The 22q11 Deletion Syndrome includes the overlapping phenotypes of DiGeorge/Velocardiofacial Syndromes, characterized by conotruncal heart defects, cleft palate, thymus, and parathyroid gland dysplasia. The majority (90%) of patients harbor detectable chr22q11.2 deletions, but a genetic etiology for the remainder of patients without a deletion can remain undefined despite major birth defects. We analyzed DNA from eight patients with normal 22q11 FISH studies by high-density single nucleotide polymorphism (SNP) arrays and identified potentially pathogenic copy number variants (CNVs) in four of eight patients. Two patients showed large CNVs in regions of known genomic disorders: one a deletion of distal chr22q11.2 and the other a duplication of chr5q35. A 3-Mb deletion of chr19p13.3 that includes a gene associated with conotruncal heart defects was found in a third patient. Two potentially pathogenic CNVs were found in a fourth patient: a large heterozygous deletion of chr6p24 and a smaller duplication of chr9p24. Our findings support a recent consensus statement advocating chromosomal microarray analysis as a first-line diagnostic approach for patients with multiple congenital anomalies. In patients with phenotypes suggestive of the 22q11.2 syndrome spectrum and normal FISH, microarray analysis can uncover the molecular basis of other genomic disorders whose features overlap those of 22q11.2 deletions.

Mouse and human phenotypes indicate a critical conserved role for ERK2 signaling in neural crest development.

Disrupted ERK1/2 (MAPK3/MAPK1) MAPK signaling has been associated with several developmental syndromes in humans; however, mutations in ERK1 or ERK2 have not been described. We demonstrate haplo-insufficient ERK2 expression in patients with a novel approximately 1 Mb micro-deletion in distal 22q11.2, a region that includes ERK2. These patients exhibit conotruncal and craniofacial anomalies that arise from perturbation of neural crest development and exhibit defects comparable to the DiGeorge syndrome spectrum. Remarkably, these defects are replicated in mice by conditional inactivation of ERK2 in the developing neural crest. Inactivation of upstream elements of the ERK cascade (B-Raf and C-Raf, MEK1 and MEK2) or a downstream effector, the transcription factor serum response factor resulted in analogous developmental defects. Our findings demonstrate that mammalian neural crest development is critically dependent on a RAF/MEK/ERK/serum response factor signaling pathway and suggest that the craniofacial and cardiac outflow tract defects observed in patients with a distal 22q11.2 micro-deletion are explained by deficiencies in neural crest autonomous ERK2 signaling.

Custom Pediatric Oncology Next-Generation Sequencing Panel Identifies Somatic Mosaicism in Archival Tissue and Enhances Targeted Clinical Care.

BACKGROUND: Disorders in the PIK3CA-related overgrowth spectrum because of somatic mosaicism are associated with segmental overgrowth of the body in conjunction with vascular, skeletal, and brain malformations such as hemimegalencephaly. A pathogenic variant may only be detectable in affected tissue and not in peripheral blood or saliva samples; therefore archival tissue may be the only relevant available specimen for testing. Although this is a common approach for cancer testing, it is not typically used for constitutional genetic disorders. METHODS: PIK3CA mosaicism was assessed with a custom pediatric oncology next-generation sequencing panel (OncoKids) designed to capture somatic mutations in pediatric malignancies. The panel covers a wide range of targets including PIK3CA and AKT1 hotspots. We used OncoKids on archival formalin-fixed, paraffin-embedded or frozen samples from seven patients with facial hemihypertrophy and lipomas, hemimegalencephaly, or hemihypertrophy with a lymphovascular malformation. The age of the archival tissue examined by next-generation sequencing ranged from two to 13 years (median 5 years). Every patient had clinical manifestations within the PIK3CA-related overgrowth spectrum and had a sample of an affected tissue available for testing from a prior surgical intervention. RESULTS: PIK3CA mosaicism was detected in all seven patients and the mutant allele fraction was lower in the lymphovascular malformation tissues (8% to 11%) than in brain (20% to 32%) and lipomatous (16% to 23%) tissues. CONCLUSIONS: Our study highlights the clinical utility of using a robust, oncology-focused next-generation sequencing assay to identify PIK3CA mosaicism in noncancer cases. It is feasible to use archival samples that are more than a decade old to obtain a molecular diagnosis, which can then be used to improve health care management.

Recurrent interstitial 1p36 deletions: Evidence for germline mosaicism and complex rearrangement breakpoints.

Deletions of chromosome 1p36 are one of the most frequently encountered subtelomeric alterations. Clinical features of monosomy 1p36 include neurocognitive impairment, hearing loss, seizures, cardiac defects, and characteristic facial features. The majority of cases have occurred sporadically, implying that genomic instability plays a role in the prevalence of the syndrome. Here, we report two siblings with mild phenotypic features of the deletion syndrome, including developmental delay, hearing loss, and left ventricular non-compaction (LVNC). Microarray analysis using bacterial artificial chromosome and oligonucleotide microarrays indicated the deletions were identical, suggesting germline mosaicism. Parental phenotypes were normal, and analysis by fluorescence in situ hybridization (FISH) did not show mosaicism. These small interstitial deletions were not detectable by conventional subtelomeric FISH analysis. To investigate the mechanism of deletion further, the breakpoints were cloned and sequenced, demonstrating the presence of a complex rearrangement. Sequence analysis of genes in the deletion interval did not reveal any mutations on the intact homologue that may have contributed to the LVNC seen in both children. This is the first report of apparent germline mosaicism for this disorder. Thus, our findings have important implications for diagnostic approaches and for recurrence risk counseling in families with a child with monosomy 1p36. In addition, our results further refine the minimal critical region for LVNC and hearing loss.

Deletion of ERK2 mitogen-activated protein kinase identifies its key roles in cortical neurogenesis and cognitive function.

The mitogen-activated protein (MAP) kinases ERK1 and ERK2 are critical intracellular signaling intermediates; however, little is known about their isoform-specific functions in vivo. We have examined the role of ERK2 in neural development by conditional inactivation of the murine mapk1/ERK2 gene in neural progenitor cells of the developing cortex. ERK MAP kinase (MAPK) activity in neural progenitor cells is required for neuronal cell fate determination. Loss of ERK2 resulted in a reduction in cortical thickness attributable to impaired proliferation of neural progenitors during the neurogenic period and the generation of fewer neurons. Mutant neural progenitor cells remained in an undifferentiated state until gliogenic stimuli induced their differentiation, resulting in the generation of more astrocytes. The mutant mice displayed profound deficits in associative learning. Importantly, we have identified patients with a 1 Mb microdeletion on chromosome 22q11.2 encompassing the MAPK1/ERK2 gene. These children, who have reduced ERK2 levels, exhibit microcephaly, impaired cognition, and developmental delay. These findings demonstrate an important role for ERK2 in cellular proliferation and differentiation during neural development as well as in cognition and memory formation.

Impact of genotype-first diagnosis: the detection of microdeletion and microduplication syndromes with cancer predisposition by aCGH.

BACKGROUND: The use of microarray-based comparative genomic hybridization has allowed the genetic diagnosis of some conditions before their full clinical presentation. This "genotype-first" diagnosis has the most clinical implications for genomic alterations that confer an elevated risk of cancer. In these cases, diagnosis before the manifestation of the patient's full phenotype dramatically impacts genetic counseling, clinical management, and eventual prognosis and survivability. METHODS: Using microarray-based comparative genomic hybridization, we tested 18,437 individuals with indications such as developmental disabilities and congenital anomalies. RESULTS: We identified 34 (0.18%) individuals with DNA copy number gains or losses that encompassed gene regions associated with recognized genetic conditions with an increased risk for cancer. Three of the 34 individuals (8.8%) had a previously abnormal cytogenetic study which microarray-based comparative genomic hybridization confirmed and/or further characterized. Seven of the 34 individuals (20.6%) either had the correct disease specified in the clinical indication for study or had clinical features highly indicative of that syndrome. The remaining 24 patients (70.6%) had indications for study that were not specific to the diagnosed syndrome, such as "developmental delay" or "dysmorphic features." CONCLUSIONS: The ability of microarray-based comparative genomic hybridization to rapidly and objectively interrogate the genome for chromosomal imbalances has led to the opportunity to optimize medical management and outcome. This has an even more profound impact and clinical utility in conditions associated with cancer predisposition syndromes.

Embryonal rhabdomyosarcoma in a patient with a germline CBL pathogenic variant.

Germline pathogenic variants in CBL are associated with an autosomal dominant RASopathy and an increased risk for malignancies, particularly juvenile myelomonocytic leukemia. Herein, we describe a patient with clinical features of a Noonan-spectrum disorder who developed embryonal rhabdomyosarcoma of the bladder at age two years. Tumor analysis using the OncoKids® cancer panel revealed a CBL pathogenic variant: NM_005188.3:c.1100A>C (p.Gln367Pro). Sanger sequencing of peripheral blood DNA confirmed a de novo heterozygous germline variant. This is the first report of embryonal rhabdomyosarcoma in association with a germline CBL pathogenic variant, further broadening the CBL cancer predisposition spectrum.

A semiautomated whole-exome sequencing workflow leads to increased diagnostic yield and identification of novel candidate variants.

Advancing the clinical utility of whole-exome sequencing (WES) for patients with suspected genetic disorders is largely driven by bioinformatics approaches that streamline data processing and analysis. Herein, we describe our experience with implementing a semiautomated and phenotype-driven WES diagnostic workflow, incorporating both the DRAGEN pipeline and the Exomiser variant prioritization tool, at an academic children's hospital with an ethnically diverse pediatric patient population. We achieved a 41% molecular diagnostic rate for 66 duo-, quad-, or trio-WES cases, and 28% for 40 singleton-WES cases. Preliminary results were returned to ordering physicians within 1 wk for 12 of 38 (32%) probands with positive findings, which were instrumental in guiding the appropriate clinical management for a variety of patients, especially in critical care settings. The semiautomated and streamlined WES workflow also enabled us to identify novel variants in candidate disease genes in patients with developmental delay and autism and immune disorders and cancer, including ANK2, BPTF, BCL11A, FOXN1, PLAA, ATRX, DNAJC21, and RAD50 Together, we demonstrated the implementation of a streamlined WES workflow that was successfully applied for both clinical and research purposes.

Intracytoplasmic sperm injection (ICSI) with transmission of a ring(Y) chromosome and ovotesticular disorder of sex development in offspring.

We present a newborn infant with ovotesticular disorder of sex development and sex chromosome mosaicism with a supernumerary ring(Y), and a normal female cell line (47,XXr(Y)[10]/46,XX[40]. The ring (Y) was inherited from the child's father, and was transmitted following assisted reproductive technology and intracytoplasmic sperm injection (ICSI). The father presented with infertility and oligospermia, but cytogenetic analysis had not been carried out as part of the infertility workup. The Y containing cell line had not been seen on amniocentesis, which had shown a 46,XX apparently normal female karyotype in all cells studied. Molecular analysis using polymorphic probes from the X chromosome demonstrated that the 47,XXr(Y) cell line in the child was consistent with inheritance from the father, following meiosis I paternal non-disjunction. This report underscores the need to obtain chromosome analysis in couples with infertility who undergo assisted reproduction.