Corrigendum: Spondyloocular syndrome: A novel XYLT2 variant with description of the neonatal phenotype.

[This corrects the article DOI: 10.3389/fgene.2021.761264.].

Heterozygosity for neuronal ceroid lipofuscinosis predisposes to bipolar disorder

Objective: Bipolar disorder is a heritable chronic mental disorder that causes psychosocial impairment through depressive/manic episodes. Familial transmission of bipolar disorder does not follow simple Mendelian patterns of inheritance. The aim of this study was to describe a large family with 12 members affected by bipolar disorder. Whole-exome sequencing was performed for eight members, three of whom were diagnosed with bipolar disorder, and another reported as "borderline." Methods: Whole-exome sequencing data allowed us to select variants that the affected members had in common, including and excluding the "borderline" individual with moderate anxiety and obsessive-compulsive traits. Results: The results favored designating certain genes as predispositional to bipolar disorder: a heterozygous missense variant in CLN6 resulted in a "borderline" phenotype that, if combined with a heterozygous missense variant in ZNF92, is responsible for the more severe bipolar disorder phenotype. Both rare missense changes are predicted to disrupt protein function. Conclusions: Loss of both alleles in CLN6 causes neuronal ceroid lipofuscinosis, a severe progressive childhood neurological disorder. Our results indicate that heterozygous CLN6 carriers, previously reported as healthy, may be susceptible to bipolar disorder later in life if associated with additional variants in ZNF92.

Natural history of KBG syndrome in a large European cohort.

KBG syndrome (KBGS) is characterized by distinctive facial gestalt, short stature and variable clinical findings. With ageing, some features become more recognizable, allowing a differential diagnosis. We aimed to better characterize natural history of KBGS. In the context of a European collaborative study, we collected the largest cohort of KBGS patients (49). A combined array- based Comparative Genomic Hybridization and next generation sequencing (NGS) approach investigated both genomic Copy Number Variants and SNVs. Intellectual disability (ID) (82%) ranged from mild to moderate with severe ID identified in two patients. Epilepsy was present in 26.5%. Short stature was consistent over time, while occipitofrontal circumference (median value: -0.88 SD at birth) normalized over years. Cerebral anomalies, were identified in 56% of patients and thus represented the second most relevant clinical feature reinforcing clinical suspicion in the paediatric age when short stature and vertebral/dental anomalies are vague. Macrodontia, oligodontia and dental agenesis (53%) were almost as frequent as skeletal anomalies, such as brachydactyly, short fifth finger, fifth finger clinodactyly, pectus excavatum/carinatum, delayed bone age. In 28.5% of individuals, prenatal ultrasound anomalies were reported. Except for three splicing variants, leading to a premature termination, variants were almost all frameshift. Our results, broadening the spectrum of KBGS phenotype progression, provide useful tools to facilitate differential diagnosis and improve clinical management. We suggest to consider a wider range of dental anomalies before excluding diagnosis and to perform a careful odontoiatric/ear-nose-throat (ENT) evaluation in order to look for even submucosal palate cleft given the high percentage of palate abnormalities. NGS approaches, following evidence of antenatal ultrasound anomalies, should include ANKRD11.

Spondyloocular Syndrome: A Novel XYLT2 Variant with Description of the Neonatal Phenotype.

Spondyloocular syndrome (SOS) is a skeletal disorder caused by pathogenic variants in XYLT2 gene encoding a xylotransferase involved in the biosynthesis of proteoglycans. This condition, with autosomal recessive inheritance, has a high phenotypic variability. It is characterized by bone abnormalities (osteoporosis, fractures), eye and cardiac defects, hearing impairment, and varying degrees of developmental delay. Until now only 20 mutated individuals have been reported worldwide. Here, we describe two siblings from consanguineous healthy parents in which a novel homozygous frameshift variant c.1586dup p(Thr530Hisfs*) in the XYLT2 gene was detected by exome sequencing (ES). The first patient (9 years) presented short stature with skeletal defects, long face, hearing loss and cataract. The second patient, evaluated at a few days of life, showed macrosomia, diffuse hypertrichosis on the back, overabundant skin in the retronucal area, flattened facial profile with drooping cheeks, elongated eyelid rims, wide and flattened nasal bridge and turned down corners of the mouth. During the prenatal period, high nuchal translucency and intestinal hyperechogenicity were observed at ultrasound. In conclusion, these two siblings with a novel pathogenic variant in XYLT2 further expand the clinical and mutational spectrum of SOS.

13q Deletion Syndrome Involving RB1: Characterization of a New Minimal Critical Region for Psychomotor Delay.

Retinoblastoma (RB) is an ocular tumor of the pediatric age caused by biallelic inactivation of the RB1 gene (13q14). About 10% of cases are due to gross-sized molecular deletions. The deletions can involve the surrounding genes delineating a contiguous gene syndrome characterized by RB, developmental anomalies, and peculiar facial dysmorphisms. Overlapping deletions previously found by traditional and/or molecular cytogenetic analysis allowed to define some critical regions for intellectual disability (ID) and multiple congenital anomalies, with key candidate genes. In the present study, using array-CGH, we characterized seven new patients with interstitial 13q deletion involving RB1. Among these cases, three patients with medium or large 13q deletions did not present psychomotor delay. This allowed defining a minimal critical region for ID that excludes the previously suggested candidate genes (HTR2A, NUFIP1, PCDH8, and PCDH17). The region contains 36 genes including NBEA, which emerged as the candidate gene associated with developmental delay. In addition, MAB21L1, DCLK1, EXOSC8, and SPART haploinsufficiency might contribute to the observed impaired neurodevelopmental phenotype. In conclusion, this study adds important novelties to the 13q deletion syndrome, although further studies are needed to better characterize the contribution of different genes and to understand how the haploinsufficiency of this region can determine ID.

Corrigendum: Exome Sequencing in BRCA1-2 Candidate Familias: The Contribution of Other Cancer Susceptibility Genes.

[This corrects the article DOI: 10.3389/fonc.2021.649435.].

Severe COVID-19 in Hospitalized Carriers of Single CFTR Pathogenic Variants.

The clinical presentation of COVID-19 is extremely heterogeneous, ranging from asymptomatic to severely ill patients. Thus, host genetic factors may be involved in determining disease presentation and progression. Given that carriers of single cystic fibrosis (CF)-causing variants of the CFTR gene-CF-carriers-are more susceptible to respiratory tract infections, our aim was to determine their likelihood of undergoing severe COVID-19. We implemented a cohort study of 874 individuals diagnosed with COVID-19, during the first pandemic wave in Italy. Whole exome sequencing was performed and validated CF-causing variants were identified. Forty subjects (16 females and 24 males) were found to be CF-carriers. Among mechanically ventilated patients, CF-carriers were more represented (8.7%) and they were significantly (p < 0.05) younger (mean age 51 years) compared to noncarriers (mean age 61.42 years). Furthermore, in the whole cohort, the age of male CF-carriers was lower, compared to noncarriers (p < 0.05). CF-carriers had a relative risk of presenting an abnormal inflammatory response (CRP ≥ 20 mg/dL) of 1.69 (p < 0.05) and their hazard ratio of death at day 14 was 3.10 (p < 0.05) in a multivariate regression model, adjusted for age, sex and comorbidities. In conclusion, CF-carriers are more susceptible to the severe form of COVID-19, showing also higher risk of 14-day death.

Exome sequencing in BRCA1-2 candidate familias: the contribution of other cancer susceptibility genes

Hereditary Breast and Ovarian Cancer (HBOC) syndrome is a condition in which the risk of breast and ovarian cancer is higher than in the general population. The prevalent pathogenesis is attributable to inactivating variants of the BRCA1-2 highly penetrant genes, however, other cancer susceptibility genes may also be involved. By Exome Sequencing (WES) we analyzed a series of 200 individuals selected for genetic testing in BRCA1-2 genes according to the updated National Comprehensive Cancer Network (NCCN) guidelines. Analysis by MLPA was performed to detect large BRCA1-2 deletions/duplications. Focusing on BRCA1-2 genes, data analysis identified 11 cases with pathogenic variants (4 in BRCA1 and 7 in BRCA1-2) and 12 with uncertain variants (7 in BRCA1 and 5 in BRCA2). Only one case was found with a large BRCA1 deletion. Whole exome analysis allowed to characterize pathogenic variants in 21 additional genes: 10 genes more traditionally associated to breast and ovarian cancer (ATM, BRIP1, CDH1, PALB2, PTEN, RAD51C, and TP53) (5% diagnostic yield) and 11 in candidate cancer susceptibility genes (DPYD, ERBB3, ERCC2, MUTYH, NQO2, NTHL1, PARK2, RAD54L, and RNASEL). In conclusion, this study allowed a personalized risk assessment and clinical surveillance in an increased number of HBOC families and to broaden the spectrum of causative variants also to candidate non-canonical genes.

Shorter androgen receptor polyQ alleles protect against life-threatening COVID-19 disease in European males.

BACKGROUND: While SARS-CoV-2 similarly infects men and women, COVID-19 outcome is less favorable in men. Variability in COVID-19 severity may be explained by differences in the host genome. METHODS: We compared poly-amino acids variability from WES data in severely affected COVID-19 patients versus SARS-CoV-2 PCR-positive oligo-asymptomatic subjects. FINDINGS: Shorter polyQ alleles (≤22) in the androgen receptor (AR) conferred protection against severe outcome in COVID-19 in the first tested cohort (both males and females) of 638 Italian subjects. The association between long polyQ alleles (≥23) and severe clinical outcome (p = 0.024) was also validated in an independent cohort of Spanish men <60 years of age (p = 0.014). Testosterone was higher in subjects with AR long-polyQ, possibly indicating receptor resistance (p = 0.042 Mann-Whitney U test). Inappropriately low serum testosterone level among carriers of the long-polyQ alleles (p = 0.0004 Mann-Whitney U test) predicted the need for intensive care in COVID-19 infected men. In agreement with the known anti-inflammatory action of testosterone, patients with long-polyQ and age ≥60 years had increased levels of CRP (p = 0.018, not accounting for multiple testing). INTERPRETATION: We identify the first genetic polymorphism that appears to predispose some men to develop more severe disease. Failure of the endocrine feedback to overcome AR signaling defects by increasing testosterone levels during the infection leads to the polyQ tract becoming dominant to serum testosterone levels for the clinical outcome. These results may contribute to designing reliable clinical and public health measures and provide a rationale to test testosterone as adjuvant therapy in men with COVID-19 expressing long AR polyQ repeats. FUNDING: MIUR project "Dipartimenti di Eccellenza 2018-2020" to Department of Medical Biotechnologies University of Siena, Italy (Italian D.L. n.18 March 17, 2020) and "Bando Ricerca COVID-19 Toscana" project to Azienda Ospedaliero-Universitaria Senese. Private donors for COVID-19 research and charity funds from Intesa San Paolo.

MET somatic activating mutations are responsible for lymphovenous malformation and can be identified using cell-free DNA next generation sequencing liquid biopsy.

OBJECTIVE: Germline mutations of either the endothelial cell-specific tyrosine kinase receptor TIE2 or the glomulin (GLMN) gene are responsible for rare inherited venous malformations. Both genes affect the hepatocyte growth factor receptor c-Met, inducing vascular smooth muscle cell migration. Germline mutations of hepatocyte growth factor are responsible for lymphatic malformations, leading to lymphedema. The molecular alteration leading to the abnormal mixed vascular anomaly defined as lymphovenous malformation has remained unknown. METHODS: A group of 4 patients with lymphovenous malformations were selected. Plasma was obtained from both peripheral and efferent vein samples at the vascular malformation site for cell-free DNA extraction. When possible, we analyzed tissue biopsy samples from the vascular lesion. RESULTS: We have demonstrated that in all four patients, an activating MET mutation was present. In three of the four patients, the same pathogenic activating mutation, T1010I, was identified. The mutation was found at the tissue level for the patient with tissue samples available, confirming its causative role in the lymphovenous malformations. CONCLUSIONS: In the present study, we have demonstrated that cell-free DNA next generation sequencing liquid biopsy is able to identify the MET mutations in affected tissues. Although a wider cohort of patients is necessary to confirm its causative role in lymphovenous malformations, these data suggest that lymphovenous malformations could result from postzygotic somatic mutations in genes that are key regulators of lymphatic development. The noninvasiveness of the method avoids any risk of bleeding and can be easily performed in children. We are confident that the present pioneering results have provided a viable alternative in the future for lymphovenous malformation diagnosis, allowing for subsequent therapy tailored to the genetic defect.

A pilot study of next generation sequencing-liquid biopsy on cell-free DNA as a novel non-invasive diagnostic tool for Klippel-Trenaunay syndrome.

OBJECTIVES: Somatic mosaicism of PIK3CA gene is currently recognized as the molecular driver of Klippel-Trenaunay syndrome. However, given the limitation of the current technologies, PIK3CA somatic mutations are detected only in a limited proportion of Klippel-Trenaunay syndrome cases and tissue biopsy remains an invasive high risky, sometimes life-threatening, diagnostic procedure. Next generation sequencing liquid biopsy using cell-free DNA has emerged as an innovative non-invasive approach for early detection and monitoring of cancer. This approach, overcoming the space-time profile constraint of tissue biopsies, opens a new scenario also for others diseases caused by somatic mutations. METHODS: In the present study, we performed a comprehensive analysis of seven patients (four females and three males) with Klippel-Trenaunay syndrome. Blood samples from both peripheral and efferent vein from malformation were collected and cell-free DNA was extracted from plasma. Tissue biopsies from vascular lesions were also collected when available. Cell-free DNA libraries were performed using Oncomine™ Pan-Cancer Cell-Free Assay. Ion Proton for sequencing and Ion Reporter Software for analysis were used (Life Technologies, Carlsbad, CA, USA). RESULTS: Cell-free circulating DNA analysis revealed pathogenic mutations in PIK3CA gene in all patients. The mutational load was higher in plasma obtained from the efferent vein at lesional site (0.81%) than in the peripheral vein (0.64%) leading to conclude for a causative role of the identified variants. Tissue analysis, available for one amputated patient, confirmed the presence of the mutation at the malformation site at a high molecular frequency (14-25%), confirming its causative role. CONCLUSIONS: Our data prove for the first time that the cell-free DNA-next generation sequencing-liquid biopsy, which is currently used exclusively in an oncologic setting, is indeed the most effective tool for Klippel-Trenaunay syndrome diagnosis and tailored personalized treatment.

Cell-free DNA next-generation sequencing liquid biopsy as a new revolutionary approach for arteriovenous malformation.

OBJECTIVE: Somatic mosaicism of KRAS gene is currently recognized as the only established molecular basis of arteriovenous malformations (AVM). However, given the limitations of the current technologies, KRAS somatic mutations are detected only in a limited proportion of AVMs and tissue biopsy remains an invasive high risky, sometimes life-threatening, diagnostic procedure. Next-generation sequencing liquid biopsy using cell-free DNA (cfDNA) has emerged as an innovative noninvasive approach for early detection and monitoring of cancer. This approach overcomes the space-time profile constraint of tissue biopsies opens a new scenario for vascular malformations owing to somatic mosaicism. Here, we propose a new approach as a fast noninvasive reliable tool in order to investigate the cfDNA coming from the AVMs. METHODS: A group of five patients suffering from AVM were selected. Blood samples from peripheral vein and efferent vein from vascular malformation were collected and cfDNA was extracted. The cfDNA libraries were performed using Oncomine Pan-Cancer Cell-Free Assay. We used Ion Proton for sequencing and Ion Reporter Software for analysis (Life Technologies, Carlsbad, Calif). RESULTS: In all cases, either G12D or G12V mutations in KRAS were identified. The mutational load was higher in the efferent vein than in peripheral blood, confirming the causative role of the identified mutation at a somatic level. CONCLUSIONS: We demonstrate that cfDNA next-generation sequencing liquid biopsy is able to identify the KRAS mutation detected in affected tissues. Moreover, we have shown that blood sample withdrawal at the lesion site increases variant allele frequency with an order of magnitude above the limit of detection (usually 0.05%), decreasing the risk of a false negative. Finally, the noninvasiveness of the method avoids any risk of bleeding, being easily performed also in children. We propose this technique as the method of choice to better investigate AVMs and consequently to identify the therapy tailored to the genetic defect. CLINICAL RELEVANCE: This article highlights the importance of using liquid biopsy as a new method to investigate the molecular profile of AVMs. In view of the frequent inaccessibility of vascular tissues owing to the invasiveness of solid biopsy and the relative high incidence of biopsies with low diagnostic power, here we evaluated the efficacy of detecting cfDNA fragments released into the bloodstream from the affected tissue cells. Through a simple blood draw from the efferent vein at the vascular malformation site, the liquid biopsy allowed us to identify KRAS pathogenic mutations piloting a personalized therapeutic approach and opening a new scenario for new therapeutic strategies.