Identification of copy-number variants in patients with overgrowth disorders.

Overgrowth syndromes (OGS) comprise a heterogeneous group of disorders whose main characteristic is that the weight, height or the head circumference are above the 97th centile or 2-3 standard deviations above the mean for age, gender, and ethnic group. Several copy-number variants (CNVs) have been associated with the development of OGS, such as the 5q35 microdeletion or the duplication of the 15q26.1-qter, among many others. In this study, we have applied 850K SNP-arrays to 112 patients and relatives with OGS from the Spanish OverGrowth Registry Initiative. We have identified CNVs associated with the disorder in nine individuals (8%). Subsequently, whole genome sequencing (WGS) analysis was performed in these nine samples in order to better understand these genomic imbalances. All the CNVs were detected by both techniques, settling that WGS is a useful tool for CNV detection. We have found six patients with genomic abnormalities associated with previously well-established disorders and three patients with CNVs of unknown significance, which may be related to OGS, based on scientific literature. In this report, we describe these findings and comment on genes associated with OGS that are located within the CNV regions.

DNA Methylation Signature for EZH2 Functionally Classifies Sequence Variants in Three PRC2 Complex Genes.

Weaver syndrome (WS), an overgrowth/intellectual disability syndrome (OGID), is caused by pathogenic variants in the histone methyltransferase EZH2, which encodes a core component of the Polycomb repressive complex-2 (PRC2). Using genome-wide DNA methylation (DNAm) data for 187 individuals with OGID and 969 control subjects, we show that pathogenic variants in EZH2 generate a highly specific and sensitive DNAm signature reflecting the phenotype of WS. This signature can be used to distinguish loss-of-function from gain-of-function missense variants and to detect somatic mosaicism. We also show that the signature can accurately classify sequence variants in EED and SUZ12, which encode two other core components of PRC2, and predict the presence of pathogenic variants in undiagnosed individuals with OGID. The discovery of a functionally relevant signature with utility for diagnostic classification of sequence variants in EZH2, EED, and SUZ12 supports the emerging paradigm shift for implementation of DNAm signatures into diagnostics and translational research.

Neuroimaging features of genetic syndromes associated with CNS overgrowth.

Overgrowth syndromes can manifest with enlargement of the brain and other body parts and are associated with malignancy. Much of the current literature focuses on the imaging findings of the somatic overgrowth, while there is relatively little describing the overgrowth of the central nervous system. In this pictorial essay, we discuss common syndromes with central nervous system overgrowth, highlight key imaging features, and review the underlying genetics, including the PI3K-AKT-mTOR pathway as well as other syndromes from various genes.

Treatment strategies for mosaic overgrowth syndromes of the PI3K-AKT-mTOR pathway.

INTRODUCTION OR BACKGROUND: Mosaic overgrowth syndromes (OS) are a proteiform ensemble of rare diseases displaying asymmetric overgrowth involving any tissue type, with degrees of severity ranging from isolated malformation to life-threatening conditions such as pulmonary embolism. Despite discordant clinical presentations, all those syndromes share common genetic anomalies: somatic mutations of genes involved in cell growth and proliferation. The PI3K-AKT-mTOR signaling pathway is one of the most prominent regulators of cell homeostasis, and somatic oncogenic mutations affecting this pathway are responsible for mosaic OS. This review aims to describe the clinical and molecular characteristics of the main OS involving the PI3K-AKT-mTOR pathway, along with the treatments available or under development. SOURCES OF DATA: This review summarizes available data regarding OS in scientific articles published in peer-reviewed journals. AREAS OF AGREEMENT: OS care requires a multidisciplinary approach relying on clinical and radiological follow-up along with symptomatic treatment. However, no specific treatment has yet shown efficacy in randomized control trials. AREAS OF CONTROVERSY: Clinical classifications of OS led to frequent misdiagnosis. Moreover, targeted therapies directed at causal mutated proteins are developing in OSs through cancer drugs repositioning, but the evidence of efficacy and tolerance is still lacking for most of them. GROWING POINTS: The genetic landscape of OS is constantly widening and molecular classifications tend to increase the accuracy of diagnosis, opening opportunities for targeted therapies. AREAS TIMELY FOR DEVELOPING RESEARCH: OS are a dynamic, expanding field of research. Studies focusing on the identification of genetic anomalies and their pharmacological inhibition are needed.

Bilateral Nephroblastic Tumors and a Complex Renal Vascular Anomaly in a Patient With a Mosaic RASopathy: Novel Histopathologic Features and Molecular Insights.

Mosaic RASopathies are an emerging group of disorders characterized by mosaic or post-zygotic activating mutations in genes of the RAS/MAPKinase signaling pathway. The phenotype is highly variable, ranging from limited or localized forms to cases with a syndromic presentation with extensive or multiorgan involvement, and also overlaps with other mosaic disorders. While there are several reports of malignancies in patients with mosaic RASopathies, specifically rhabdomyosarcoma and transitional urothelial carcinoma, the lifetime risk and molecular mechanisms that lead to the development of malignancies remain unclear. We report a 22-month-old boy with a somatic RASopathy due to an underlying KRAS p.G12D mutation who presented with a large unilateral epidermal nevus, asymmetric lower limb overgrowth with lytic and sclerotic bone lesions, capillary malformation, bilateral nephrogenic rests and Wilms tumors, and a novel complex renal vascular anomaly that resembles Fibro-Adipose Vascular Anomaly (FAVA). This report further expands the phenotypic spectrum of somatic RASopathies, and discusses the potential phenotypic and pathogenetic overlap with PIK3CA-related overgrowth disorders, specifically CLOVES. The occurrence of a secondary cancer hotspot mutation (FBXW7 p.R479G) in the Wilms tumor, but not the associated nephrogenic rest, moreover suggests that additional driver mutations are involved in the development of Wilms tumor in somatic overgrowth disorders.

Kagami-Ogata syndrome: an important differential diagnosis to Beckwith-Wiedemann syndrome.

We report the case of a fetus with sonographic characteristics of Beckwith-Wiedemann syndrome (BWS). A 30-year-old gravida 2 para 1 was referred to our fetal medicine unit with an omphalocele. Fetal macrosomia, organomegaly, and polyhydramnios but no macroglossia were detected and BWS was suspected. Genetic testing for BWS did not confirm the suspected diagnosis as the karyotype was normal. Symptomatic polyhydramnios led to repeated amnioreductions. At 35 + 5 weeks of gestation, a female neonate of 3660 g was delivered with APGAR scores of 6/7/8, after 1/5/10 min, respectively. The abnormal shape of the thorax, facial dysmorphism, need for ventilation, and generalized muscular hypotonia led to the suspicion of Kagami-Ogata syndrome (KOS), which was confirmed by genetic testing. KOS in our patient was caused by a large deletion in the MEG3-region on chromosome 14q32 affecting the maternal allele. In this report, we highlight the notion that when sonographic signs suggestive of BWS such as macrosomia, polyhydramnios, and omphalocele are present and genetic testing does not confirm the suspected diagnosis, KOS should be tested for.

Comprehensive molecular and clinicopathological analysis of vascular malformations: A study of 319 cases.

Vascular malformations are part of overgrowth syndromes characterized by somatic mosaic mutations or rarely by germline mutations. Due to their similarities and diversity, clinicopathological classification can be challenging. A comprehensive targeted Next Generation Sequencing screen using Unique Molecular Identifiers with a technical sensitivity of 1% mutant alleles was performed for frequently mutated positions in ≥21 genes on 319 formalin-fixed paraffin-embedded samples. In 132 out of 319 cases pathogenic mosaic mutations were detected affecting genes previously linked to vascular malformations e.g. PIK3CA (n=80), TEK (TIE2) (n=11), AKT1 (n=1), GNAQ (n=7), GNA11 (n=4), IDH1 (n=3), KRAS (n=9), and NRAS (n=1). Six cases harbored a combination of mutations in PIK3CA and in GNA11 (n=2), GNAQ (n=2), or IDH1 (n=2). Aberrations in PTEN and RASA1 with a variant allele frequency approaching 50% suggestive of germline origin were identified in six out of 102 cases tested; four contained a potential second hit at a lower allele frequency. Ninety-one of the total 142 pathogenic mutations were present at a variant allele frequency <10% illustrating the importance of sensitive molecular analysis. Clinicopathological characteristics showed a broad spectrum and overlap when correlated with molecular data. Sensitive screening of recurrently mutated genes in vascular malformations may help to confirm the diagnosis and reveals potential therapeutic options with a significant contribution of PIK3CA/mTOR and RAS-MAPK pathway mutations. The co-existence of two activating pathogenic mutations in parallel pathways illustrates potential treatment challenges and underlines the importance of multigene testing. Detected germline mutations have major clinical impact.

Laser ablation of embryonic veins in children.

BACKGROUND: Klippel-Trenaunay syndrome (KTS) and related overgrowth syndromes are rare conditions that often present to academic pediatric units and multidisciplinary vascular anomaly clinics. These conditions are commonly associated with abnormalities of the superficial and deep venous structures and carry an increased risk of venous thromboembolism. METHODS: A retrospective chart review was completed of all patients treated at Johns Hopkins All Children's Hospital with endovenous laser ablation therapy (EVLT) for management of dilated embryonic veins in the setting of limb overgrowth. RESULTS: Three patients with limb overgrowth underwent EVLT between 2015 and 2017. All patients had successful occlusion of the targeted veins on post-procedure imaging. One patient developed a cellulitis successfully treated with oral antibiotics. CONCLUSIONS: Endovenous laser ablation therapy is a well-tolerated and safe procedure for prophylactic closure of abnormal superficial embryonic veins. This study supports the use of this technique in managing increased thromboembolic risk in this unique patient population and recognizes the need for a long-term study to determine its efficacy.

Characterization of the hepatosplenic and portal venous findings in patients with Proteus syndrome.

Proteus syndrome (PS) is a rare disorder caused by a mosaic AKT1 variant that comprises patchy overgrowth of tissues derived from all three germinal layers affecting multiple viscera. We sought to delineate the extent of hepatoportal manifestations in patients with PS. We identified patients with PS who had abdominal imaging from 1989 to 2015 in a natural history study. Imaging was characterized for evidence of focal findings in the liver, spleen, and portal vasculature and for organomegaly. Relevant clinical and laboratory data were compared among those with or without organomegaly. Abdominal imaging was available on 38 patients including 20 who had serial studies. Nine patients had focal hepatic lesions including vascular malformations (VMs). Focal splenic abnormalities were noted in seven patients. Patients without cutaneous VMs did not have visceral VMs. Nine patients had splenomegaly, 12 had portal vein dilation, and 4 had hepatomegaly. There was a weak correlation of portal vein dilation to spleen height ratio (r2 = 0.18, p < .05). On laboratory evaluation, hepatic function was normal but there was thrombocytopenia in those with splenomegaly; platelet counts were 179 ± 87K/µL compared to those with normal spleen size at 253 ± 57K/µL (p < .05). Overall, focal hepatosplenic abnormalities occurred in 11 of 38 (29%) patients with PS. Splenomegaly and portal venous dilation were both found in 8 of 38 (21%) patients; however, other than relative thrombocytopenia, there was no evidence of portal hypertension. Although the AKT1-E17K somatic variant is a suspected oncogene, there were no malignant lesions identified in this study.

For Debate: The Significance of Etiologic Diagnosis in Neonates with Overgrowth Syndromes. Lesson Learned from the Simpson-Golabi-Behmel Syndrome.

Overgrowth syndromes are rare genetic disorders characterized by excessive pre- and postnatal growth accompanied by dysmorphic features and developmental disorders. In addition to other health hazards, the life expectancy of affected children may be compromised due to an increased risk of developing tumors. To demonstrate the need for early recognition, correct diagnostic evaluation and adequate follow-up, we present a family with recurrent Simpson-Golabi-Behmel syndrome (SGBS). SGBS is a X-linked neonatal overgrowth syndrome caused by mutations in the GPC3 or GPC4 genes. All three affected males manifested with congenital diaphragmatic hernia. When fetal overgrowth and congenital diaphragmatic hernia co-occur, the choice for a possible cause is limited among SGBS, Marfan syndrome and Pallister-Killian syndrome. Their different phenotypes allow clinical assessment and correct diagnosis in most cases and should be followed by genetic testing. Regular oncologic screening aimed towards early recognition of malignant tumors may improve long-term outcomes in SGBS as well as in all other overgrowth syndromes.

CLOVES syndrome: review of a PIK3CA-related overgrowth spectrum (PROS).

Overgrowth syndromes are characterized by global or localized disproportionate growth associated with other anomalies, including vascular malformations and neurological and/or visceral disorders. CLOVES (Congenital Lipomatous asymmetric Overgrowth of the trunk with lymphatic, capillary, venous, and combined-type Vascular malformations, Epidermal naevi, Scoliosis/Skeletal and spinal anomalies) is an overgrowth syndrome caused by mosaic activating mutation in gene PIK3CA, which gives rise to abnormal PI3K-AKT-mTOR pathway activation. These mutations are responsible for the clinical manifestations of the syndrome, which include low- and high-flow vascular malformations, thoracic lipomatous hyperplasia, asymmetric growth, and visceral and neurological disorders. These common anomalies are illustrated with figures from two personal cases. Identification of the clinical and genetic characteristics of CLOVES syndrome is crucial for the differential diagnosis with other overgrowth syndromes, such as Proteus or Klippel-Trenaunay (K-T) syndromes, and for the therapeutic management of the different anomalies. In this context, a new entity comprising different syndromes with phenotypic mutations in PIK3CA has been proposed, designated PIK3CA-related overgrowth spectrum (PROS), with the aim of facilitating clinical management and establishing appropriate genetic study criteria.

[Overgrowth in children and in adults: novel clinical view, novel genes, novel phenotypes]. / Nadmerný rust u detí a dospelých: nový klinický pohled, nové geny, nové fenotypy.

Novel genetic findings allow to more reliably elucidate the aetiology and pathogenesis of overgrowth syndromes in children and in adults. The relatively prevalent overgrowth syndromes in foetuses and neonates include Beckwith-Wiedemann (BWS) and Sotos syndromes; in addition, several rare conditions may occur e.g. Simpson-Golabi-Behmel and Weaver syndromes. These syndromes are not connected with overproduction of growth hormone. Their carriers are at risk of hypoglycaemia (in BWS), of congenital malformations and of childhood tumours. Targeted oncologic screening may improve the outcomes. Despite rapid growth even postnatally, the final height is mostly normal. In childhood and adolescence, the increased growth velocity results from hormonal overproduction - of precocious production of sexual hormones, hyperthyroidism, or of growth hormone overproduction due to pituitary adenoma that may lead to gigantism or acrogigantism and may be familiar (familiar isolated pituitary adenoma; FIPA). In 15-25 % of affected families, FIPA is caused by autosomal dominantly inherited mutations of AIP gene encoding a tumour suppressor protein named AIP (aryl hydrocarbon receptor-interacting protein). X-linked acrogigantism (X-LAG) is due to GPR101 gene mutations or microduplications of Xq26 chromosomal region. GPR101 encodes G-protein coupled receptor with unknown ligand. X-LAG is associated with recurrent and highly-penetrant pituitary macroadenomas. Mutations of additional at least 10 genes may lead to pituitary tumour with growth hormone overproduction. Gigantism in adults results from untreated or insufficiently treated pituitary adenoma in childhood. Some of the well-known current or past giants were found to carry pathogenic genetic variants of GPR101 or AIP.

CLOVES syndrome.

A cohort of patients with overgrowth syndromes has been identified with congenital lipomatous overgrowth, dysregulated fat deposits, and mixed vascular malformations. The acronym CLOVES was given on a heuristic basis to stand for congenital lipomatous overgrowth (CLO), vascular malformation (V), epidermal nevi (E), and scoliosis and spinal deformities (S). These patients have upper limb anomalies with variable phenotypes. Although hand anomalies alone cannot make the diagnosis, the foot, truncal, cutaneous and spinal anomalies are particularly diagnostic. CLOVES syndrome has emerged as a distinct clinical entity diagnosed by clinical and radiographic examinations. The overgrowth pattern is now easily distinguished from other overgrowth syndromes.

Clinical and auxological characteristics and quality of life of 50 children and adolescents with segmental overgrowth syndromes at a single center. / Clínica, auxología y calidad de vida en cincuenta niños, niñas y adolescentes con síndromes de sobrecrecimiento corporal segmentario de un único centro.

Introduction. Segmental overgrowth syndromes are a group of rare diseases characterized by overgrowth in one or more parts of the body, mostly related to mosaic mutations in the AKT/PI3K/mTOR and RAS- MAPK signaling pathway. Our objective was to analyze the clinical and auxological characteristics and health-related quality of life (HRQoL) in this group of patients at a tertiary care hospital. Population and methods. Cross-sectional study of a follow-up cohort. Age, sex, sociodemographic data, anthropometric measurements of the affected and contralateral segments, complications, treatment, quality of life (PedsQL 4.0), and pain were analyzed. Central and dispersion measures were estimated. A univariate analysis between the quality of life and study variables was done. Results. A total of 50 patients were included; 29 were males. Median age: 9.95 (r: 1.44-17.81) years. The most common diagnosis was PIK3CA-related overgrowth spectrum (PROS) (37/50). The median number of affected segments was 2 (r: 1-7) per patient. Vascular malformations were observed in 40, and capillary malformations, in 20 patients. Pain was the most common complication (24/50). An asymmetry of the lower extremities of < 5 cm was observed in 31 patients. In most children, height was between the 50th and 97th percentiles. A lower HRQoL was observed among girls, patients with complex vascular malformations, and those with unmet basic needs (UBNs). Conclusions. PROS was the most common diagnosis. Pain was the most common complication. HRQoL was lower among girls, patients with combined vascular malformations, and those with UBNs.

Introducción. Los síndromes de sobrecrecimiento corporal segmentario son un grupo de enfermedades poco frecuentes caracterizadas por exceso de crecimiento en una o más partes del cuerpo relacionadas, en su mayoría, con mutaciones en mosaico en la vía de señalización AKT/PI3K/mTOR y RAS-MAPK. Nuestro objetivo fue analizar las características clínicas y auxológicas, y la calidad de vida relacionada a salud (CVRS) en este grupo de pacientes en un hospital de tercer nivel de atención. Población y métodos. Estudio transversal de una cohorte en seguimiento. Se analizaron edad, sexo, datos sociodemográficos, mediciones antropométricas del segmento afectado y del contralateral, complicaciones, tratamiento, calidad de vida (PedsQL4.0) y dolor. Se calcularon medidas centrales y de dispersión. Se realizó análisis univariado entre calidad de vida y variables incluidas. Resultados. Se incluyeron 50 pacientes, 29 varones. Mediana de edad 9,95 (r 1,44-17,81) años. El diagnóstico más frecuente fue síndrome de sobrecrecimiento relacionado a PIK3CA (PROS) (37/50). Mediana de número de segmentos afectados 2 (r: 1-7) por niño. Cuarenta casos presentaron malformación vascular; 20, capilar. El dolor (24/50) fue la complicación más frecuente. Treinta y un pacientes mostraron asimetría de longitud de miembros inferiores, < 5 cm. La estatura se ubicó entre los centilos 50 y 97 en la mayoría de los niños. Menor CVRS se observó en mujeres, en pacientes con malformación vascular compleja y necesidades básicas insatisfechas (NBI). Conclusiones. PROS fue el diagnóstico más frecuente. El dolor fue una complicación frecuente. La CVRS fue menor en mujeres, pacientes con malformación vascular combinada y NBI.

Brain overgrowth associated with megalencephaly-capillary malformation syndrome causing progressive Chiari and syringomyelia.

Background: Megalencephaly-capillary malformation (M-CM) syndrome is a rare overgrowth syndrome characterized by macrocephaly, port-wine stains, asymmetric brain growth, hydrocephalus, and developmental delay. Cerebellar tonsil herniation is often seen, but rarely with syringomyelia. Case Description: A newborn with M-CM syndrome developed a progressive Chiari malformation type I (CM-I) with syringomyelia. At 4 months, he was treated for subdural hematomas, while at 10 months, he required a shunt for hydrocephalus. At 16 years of age, he newly presented a left hemiparesis and ataxia. Notably, successive volumetric measurements of the posterior fossa/cerebellum showed disproportionate cerebellar growth over time that correlated with the appearance of a CM-I. Following a suboccipital craniectomy with C1-laminectomy and duraplasty, he neurologically improved. Conclusion: M-CM with CM-I and syringomyelia rarely present together. Here, we treated an infant with M-CM who developed a progressive CM-I malformation and syringomyelia reflecting disproportionate growth of the cerebellum/posterior fossa over a 16-year period.

SIMPSON-GOLABI-BEHMEL syndrome type 1: How placental immunohistochemistry can rapidly Predict the diagnosis.

INTRODUCTION: Glypican-3 (GPC3) is an oncofetal protein involved in cellular signaling, strongly expressed in the placenta, absent or diminished in postnatal life, but often increased in human malignancies. Germline loss-of-function variants of GPC3 gene are associated with Simpson-Golabi-Behmel syndrome type 1 (SGBS1), a rare recessive X-linked overgrowth disease characterized by typical facial features, congenital abnormalities, and an increased risk of developing childhood cancers. METHODS: A clinical suspicion of SGBS1 was postulated for a newborn with prenatal history of overgrowth and polyhydramnios, presenting with neonatal weight and length >99th percentile, coarse facies, iris and retinal coloboma, supernumerary nipples, and splenomegaly. While waiting for whole-genome sequencing (WGS) results, we investigated placental GPC3 immunohistochemical expression in the proband, in three additional cases of SGBS1, and disorders commonly associated with fetal macrosomia and/or placentomegaly. RESULTS: WGS in the proband identified a likely pathogenic maternally inherited missense variant in GPC3: c.1645A > G, (p.Ile549Val), and GPC3 immunohistochemistry demonstrated full-thickness loss of stain of the placental parenchyma. The same pattern ("null") was also present in the placentas of three additional cases of SGBS1, but not in those of unaffected controls. DISCUSSION: Immunohistochemical expression of GPC3 in the placenta is highly reproducible. Our findings showed that a "null pattern" of staining is predictive of SGBS1 and represents a valuable aid in the differential diagnosis of fetal macrosomias, allowing targeted genetic testing and earlier diagnosis.

Evaluation and management of the lateral marginal vein in Klippel-Trénaunay and other PIK3CA-related overgrowth syndromes.

The lateral marginal vein is an anomalous clinical entity found in association with Klippel-Trénaunay and other PIK3CA-related overgrowth syndromes. Although it is reported to affect <20% of patients with Klippel-Trénaunay syndrome, this venous anomaly has been associated with significant morbidity and mortality attributable to venous hypertension and potentially lethal thromboembolic events. Limited literature exists on the diagnosis and management of this rare anomaly, with most of the reports focusing on retrospective clinical experience at a few centers of excellence. Despite these limitations, a systematic approach to diagnosis and treatment of this anomaly is warranted and expounded on herein. When plausible, clinical recommendations based on best available literature are made.

Cancer-Associated PIK3CA Mutations in Overgrowth Disorders.

PIK3CA is one of the most commonly mutated genes in solid cancers. PIK3CA mutations are also found in benign overgrowth syndromes, collectively known as PIK3CA-related overgrowth spectrum (PROS). As in cancer, PIK3CA mutations in PROS arise postzygotically, but unlike in cancer, these mutations arise during embryonic development, with their timing and location critically influencing the resulting disease phenotype. Recent evidence indicates that phosphoinositide 3-kinase (PI3K) pathway inhibitors undergoing trials in cancer can provide a therapy for PROS. Conversely, PROS highlights gaps in our understanding of PI3K's role during embryogenesis and in cancer development. Here, we summarize current knowledge of PROS, evaluate challenges and strategies for disease modeling, and consider the implications of PROS as a paradigm for understanding activating PIK3CA mutations in human development and cancer.

PIK3CA c.3140A>G mutation in a patient with suspected Proteus Syndrome: a case report.

We present a patient with suspected Proteus Syndrome, an overgrowth disorder associated with AKT1c.49G>A mutation. NGS analysis detected PIK3CAc.3140A>G mutation in the patient's affected tissue allowing for PROS (PIK3CA-related overgrowth spectrum) diagnosis. The overlapping clinical features in overgrowth disorders highlight the importance of molecular testing for a correct diagnosis.