Goran Cuturilo

4q34.1–q35.2 deletion in a boy with phenotype resembling 22q11.2 deletion syndrome

Small terminal or interstitial deletions involving bands 4q34 and 4q35 have been described in several patients with a relatively mild phenotype such as mild to moderate intellectual disability and minor dysmorphic features. We present a boy born from unrelated parents with a de novo 4q34.1–q35.2 deletion and clinical features resembling 22q11.2 deletion syndrome. To the best of our knowledge, this is the first reported patient with 4q34–q35 deletion and phenotype resembling 22q11.2 deletion syndrome without fifth finger anomalies as a specific feature of 4q- syndrome. G-banding karyotyping disclosed the deletion, which was further delineated by microarray comparative genomic hybridization. Fluorescence in situ hybridization and multiplex ligation-dependent probe amplification analyses did not reveal rearrangements of 22q11.2 region. MLPA confirmed the deletion within the 4q35.2 region. Conclusion: Given the considerable clinical overlaps between the 22q11.2 deletion syndrome and clinical manifestation of the patient described in this study, we propose that region 4q34.1–q35.2 should be considered as another region associated with phenotype resembling 22q11.2 deletion syndrome. We also propose that distal 4q deletions should be considered in the evaluation of patients with phenotypic manifestations resembling 22q11.2 deletion syndrome in whom no 22q11.2 microdeletion was detected, even in the absence of distinctive fifth finger anomalies. Additionally, we underline the importance of applying array CGH that enables simultaneous genome-wide detection and delineation of copy number changes (e.g., deletions and duplications).

Structural, Functional, and Clinical Characterization of a Novel PTPN11 Mutation Cluster Underlying Noonan Syndrome

Germline mutations in PTPN11, the gene encoding the Src‐homology 2 (SH2) domain‐containing protein tyrosine phosphatase (SHP2), cause Noonan syndrome (NS), a relatively common, clinically variable, multisystem disorder. Here, we report on the identification of five different PTPN11 missense changes affecting residues Leu261, Leu262, and Arg265 in 16 unrelated individuals with clinical diagnosis of NS or with features suggestive for this disorder, specifying a novel disease‐causing mutation cluster. Expression of the mutant proteins in HEK293T cells documented their activating role on MAPK signaling. Structural data predicted a gain‐of‐function role of substitutions at residues Leu262 and Arg265 exerted by disruption of the N‐SH2/PTP autoinhibitory interaction. Molecular dynamics simulations suggested a more complex behavior for changes affecting Leu261, with possible impact on SHP2s catalytic activity/selectivity and proper interaction of the PTP domain with the regulatory SH2 domains. Consistent with that, biochemical data indicated that substitutions at codons 262 and 265 increased the catalytic activity of the phosphatase, while those affecting codon 261 were only moderately activating but impacted substrate specificity. Remarkably, these mutations underlie a relatively mild form of NS characterized by low prevalence of cardiac defects, short stature, and cognitive and behavioral issues, as well as less evident typical facial features.

PITX2 deficiency and associated human disease: insights from the zebrafish model

Abstract The PITX2 (paired-like homeodomain 2) gene encodes a bicoid-like homeodomain transcription factor linked with several human disorders. The main associated congenital phenotype is Axenfeld-Rieger syndrome, type 1, an autosomal dominant condition characterized by variable defects in the anterior segment of the eye, an increased risk of glaucoma, craniofacial dysmorphism and dental and umbilical anomalies; in addition to this, one report implicated PITX2 in ring dermoid of the cornea and a few others described cardiac phenotypes. We report three novel PITX2 mutations—c.271C > T, p.(Arg91Trp); c.259T > C, p.(Phe87Leu); and c.356delA, p.(Gln119Argfs*36)—identified in independent families with typical Axenfeld-Rieger syndrome characteristics and some unusual features such as corneal guttata, Wolf-Parkinson-White syndrome, and hyperextensibility. To gain further insight into the diverse roles of PITX2/pitx2 in vertebrate development, we generated various genetic lesions in the pitx2 gene via TALEN-mediated genome editing. Affected homozygous zebrafish demonstrated congenital defects consistent with the range of PITX2-associated human phenotypes: abnormal development of the cornea, iris and iridocorneal angle; corneal dermoids; and craniofacial dysmorphism. In addition, via comparison of pitx2M64* and wild-type embryonic ocular transcriptomes we defined molecular changes associated with pitx2 deficiency, thereby implicating processes potentially underlying disease pathology. This analysis identified numerous affected factors including several members of the Wnt pathway and collagen types I and V gene families. These data further support the link between PITX2 and the WNT pathway and suggest a new role in regulation of collagen gene expression during development.

Neuroimaging findings in Mowat-Wilson syndrome: a study of 54 patients

Purpose:Mowat–Wilson syndrome (MWS) is a genetic disease characterized by distinctive facial features, moderate to severe intellectual disability, and congenital malformations, including Hirschsprung disease, genital and eye anomalies, and congenital heart defects, caused by haploinsufficiency of the ZEB2 gene. To date, no characteristic pattern of brain dysmorphology in MWS has been defined.Methods:Through brain magnetic resonance imaging (MRI) analysis, we delineated a neuroimaging phenotype in 54 MWS patients with a proven ZEB2 defect, compared it with the features identified in a thorough review of published cases, and evaluated genotype–phenotype correlations.Results:Ninety-six percent of patients had abnormal MRI results. The most common features were anomalies of corpus callosum (79.6% of cases), hippocampal abnormalities (77.8%), enlargement of cerebral ventricles (68.5%), and white matter abnormalities (reduction of thickness 40.7%, localized signal alterations 22.2%). Other consistent findings were large basal ganglia, cortical, and cerebellar malformations. Most features were underrepresented in the literature. We also found ZEB2 variations leading to synthesis of a defective protein to be favorable for psychomotor development and some epilepsy features but also associated with corpus callosum agenesis.Conclusion:This study delineated the spectrum of brain anomalies in MWS and provided new insights into the role of ZEB2 in neurodevelopment.Genet Med advance online publication 10 November 2016

Wiskott-Aldrich syndrome with macrothrombocytopenia

BackgroundWiskott-Aldrich syndrome is a rare X-linked immunodeficiency disorder with a variable phenotype.Case Characteristics3.5-year-old boy diagnosed with Wiskott-Aldrich syndrome.ObservationUnusual and persistent thrombocytopenia with increased platelet volume (>10fL). He did not exhibit characteristic clinical and laboratory finding for the syndrome.OutcomeMaternally inherited causative mutation in the exon 2 of the WAS gene was disclosed.MessageThis is a need for multidisciplinary assessment of patients with congenital or early infantile thrombocytopenia, including testing for mutations of the WAS gene in all unexplained cases even in the absence of characteristic microthrombocytopenia.

The novel RAF1 mutation p.(Gly361Ala) located outside the kinase domain of the CR3 region in two patients with Noonan syndrome, including one with a rare brain tumor

Noonan syndrome is characterized by typical craniofacial dysmorphism, postnatal growth retardation, congenital heart defect, and learning difficulties and belongs to the RASopathies, a group of neurodevelopmental disorders caused by germline mutations in genes encoding components of the RAS‐MAPK pathway. Mutations in the RAF1 gene are associated with Noonan syndrome, with a high prevalence of hypertrophic cardiomyopathy (HCM). RAF1 mutations cluster in exons encoding the conserved region 2 (CR2), the kinase activation segment of the CR3 domain, and the C‐terminus. We present two boys with Noonan syndrome and the identical de novo RAF1 missense variant c.1082G>C/p.(Gly361Ala) affecting the CR3, but located outside the kinase activation segment. The p.(Gly361Ala) mutation has been identified as a RAF1 allele conferring resistance to RAF inhibitors. This amino acid change favors a RAF1 conformation that allows for enhanced RAF dimerization and increased intrinsic kinase activity. Both patients with Noonan syndrome showed typical craniofacial dysmorphism, macrocephaly, and short stature. One individual developed HCM and was diagnosed with a disseminated oligodendroglial‐like leptomeningeal tumor (DOLT) of childhood at the age of 9 years. While there is a well‐established association of NS with malignant tumors, especially childhood hemato‐oncological diseases, brain tumors have rarely been reported in Noonan syndrome. Our data demonstrate that mutation scanning of the entire coding region of genes associated with Noonan syndrome is mandatory not to miss rare variants located outside the known mutational hotspots.

Prenatal growth retardation, microcephaly, and eye coloboma in infant with multiple congenital anomalies: Further delineation of presumed new dysmorphic syndrome

BACKGROUND Ten years ago an unusual association of prenatal growth retardation, microcephaly, coloboma of the iris/eye anomalies, congenital heart defects, and urogenital anomalies was reported for the first time in three siblings. Autosomal recessive inheritance was presumed. This finding has been included in London Winter-Baraitser Dysmorphology Database as a separate entity, but still has not been classified as a distinct syndrome. CASE We report an infant with an association of prenatal growth retardation, microcephaly, facial dysmorphism, eye anomalies, congenital heart defects, and testis retention. Mild craniofacial dysmorphism consists of sloped forehead, bulbous nose tip, and micrognathia. Eye anomalies include coloboma of the iris, choroidea, and optic nerve as well as lens dislocation. The patient also presents with ventricular and atrial septal defects, hypoplastic mitral valve, persistent left superior vena cava, accessory spleen, and club foot. CONCLUSIONS To the best of our knowledge, this is the second family and the fourth case with this pattern of birth defects reported worldwide so far. We presume that this combination of multiple congenital anomalies and growth retardation constitutes a newly recognized syndrome of likely autosomal recessive inheritance. So far no data suggest etiological impact of consanguinity, parental age, or environmental factors.

Comprehensive use of extended exome analysis improves diagnostic yield in rare disease: a retrospective survey in 1,059 cases

PurposeWe sought to determine the analytical sensitivity of several extended exome variation analysis approaches in terms of their contribution to diagnostic yield and their clinical feasibility.MethodsWe retrospectively analyzed the results of genetic testing in 1,059 distinct cases referred for exome sequencing to our institution. In these, we routinely employed extended exome analysis approaches in addition to basic variant analysis, including (i) copy-number variation (CNV) detection, (ii) nonconsensus splice defect detection, (ii) genomic breakpoint detection, (iv) homozygosity mapping, and (v) mitochondrial variant analysis.ResultsExtended exome analysis approaches assisted in identification of causative genetic variant in 44 cases, which represented a 4.2% increase in diagnostic yield. The greatest contribution was associated with CNV analysis (1.8%) and splice variant prediction (1.2%), and the remaining approaches contributed an additional 1.2%. Analysis of workload has shown that on average nine additional variants per case had to be interpreted in the extended analysis.ConclusionWe show that extended exome analysis approaches improve the diagnostic yield of heterogeneous genetic disorders and result in considerable increase of diagnostic yield of exome sequencing with a minor increase of interpretative workload.

Differences in speech and language abilities between children with 22q11.2 deletion syndrome and children with phenotypic features of 22q11.2 deletion syndrome but without microdeletion.

BACKGROUND 22q11.2DS is the most common microdeletion syndrome in humans, usually associated with speech and language delay (SLD). Approximately 75% of children with 22q11.2 microdeletion have congenital heart malformations (CHM) which after infant open-heart surgery might lead to SLD. AIMS The purpose of this study was to determine whether factors associated with microdeletion contribute to SLD in children with 22q11.2DS. METHODS AND PROCEDURES We compared speech and language abilities of two groups of school-aged children: those with 22q11.2 microdeletion (E1) and those with the phenotype resembling 22q11.2DS but without the microdeletion (E2). An age-matched group of typically developing children was also tested. OUTCOMES AND RESULTS The obtained results revealed that children from group E1 have lower level of speech and language abilities compared to children from group E2 and control group. Additionally, mild to moderate SLD was detected in children from group E2 compared to children from the control group. CONCLUSIONS AND IMPLICATIONS The obtained results imply that both CHM after infant open-heart surgery and other factors associated with 22q11.2 microdeletion, contribute to SLD in patients with 22q11.2 microdeletion. Based on this, we could postulate that there is/are some potential candidate gene(s), located in the 22q11.2 region, whose function could be important for speech and language development.

Inhaled nitric oxide therapy for acute respiratory distress syndrome in children.

The aim of this study was to evaluate the effects of inhaled nitric oxide (iNO) therapy on oxygenation and mortality in children with acute respiratory distress syndrome (ARDS). Thirty-three children with ARDS and an arterial SatO2 <88% despite mechanical ventilation were analyzed. Patients in the iNO group were prospectively enrolled and treated with conventional therapy plus iNO. The control group consisted of retrospectively analyzed patients treated only with conventional therapy. A significant increase in PaO2/FiO2 ratio (25.6%) and decrease in oxygenation index (19.5%) was observed after 4 h of iNO treatment, when compared to baseline values. A positive response to iNO was detected in 69% of patients, and there was no difference between pulmonary and extrapulmonary ARDS. There was no difference in mortality and duration of mechanical ventilation between iNO and control group.