A deep phenotyping experience: up to date in management and diagnosis of Malan syndrome in a single center surveillance report.

BACKGROUND: Malan syndrome (MALNS) is a recently described ultrarare syndrome lacking guidelines for diagnosis, management and monitoring of evolutive complications. Less than 90 patients are reported in the literature and limited clinical information are available to assure a proper health surveillance. RESULTS: A multidisciplinary team with high expertise in MALNS has been launched at the "Ospedale Pediatrico Bambino Gesù", Rome, Italy. Sixteen Italian MALNS individuals with molecular confirmed clinical diagnosis of MALNS were enrolled in the program. For all patients, 1-year surveillance in a dedicated outpatient Clinic was attained. The expert panel group enrolled 16 patients and performed a deep phenotyping analysis directed to clinically profiling the disorder and performing critical revision of previously reported individuals. Some evolutive complications were also assessed. Previously unappreciated features (e.g., high risk of bone fractures in childhood, neurological/neurovegetative symptoms, noise sensitivity and Chiari malformation type 1) requiring active surveillance were identified. A second case of neoplasm was recorded. No major cardiovascular anomalies were noticed. An accurate clinical description of 9 new MALNS cases was provided. CONCLUSIONS: Deep phenotyping has provided a more accurate characterization of the main clinical features of MALNS and allows broadening the spectrum of disease. A minimal dataset of clinical evaluations and follow-up timeline has been proposed for proper management of patients affected by this ultrarare disorder.

Congenital heart defects in molecularly confirmed KBG syndrome patients.

Congenital heart defects (CHDs) are known to occur in 9%-25% of patients with KBG syndrome. In this study we analyzed the prevalence and anatomic types of CHDs in 46 personal patients with KBG syndrome, carrying pathogenetic variants in ANKRD11 or 16q24.3 deletion, and reviewed CHDs in patients with molecular diagnosis of KBG syndrome from the literature. CHD was diagnosed in 15/40 (38%) patients with ANKRD11 variant, and in one patient with 16q24.3 deletion. Left ventricular outflow tract obstructions have been diagnosed in 9/15 (60%), subaortic or muscular ventricular septal defect in 5/15 (33%), dextrocardia in 1/15 (8%). The single patient with 16q24.3 deletion and CHD had complete atrioventricular septal defect (AVSD) with aortic coarctation. Review of KBG patients from the literature and present series showed that septal defects have been diagnosed in 44% (27/61) of the cases, left ventricular tract obstructions in 31% (19/61), AVSD in 18% (11/61). Septal defects have been diagnosed in 78% of total patients with 16q24.3 deletion. Valvar anomalies are frequently diagnosed, prevalently involving the left side of the heart. A distinctive association with AVSD is identifiable and could represent a marker to suggest the diagnosis in younger patients. In conclusion, after precise molecular diagnosis and systematic cardiological screening the prevalence of CHD in KBG syndrome seems to be higher than previously reported in clinical articles. In addition to septal defects, left-sided anomalies and AVSD should be considered. Clinical management of KBG syndrome should include accurate and detailed echocardiogram at time of diagnosis.

Ketogenic diet as elective treatment in patients with drug-unresponsive hyperinsulinemic hypoglycemia caused by glucokinase mutations.

BACKGROUND: Hyperinsulinemic hypoglycemia (HI) is the most frequent cause of recurrent hypoglycemia in children. Despite diagnostic and therapeutic advances, it remains an important cause of morbidity, leading to neurological complications, such as psychomotor retardation and epilepsy. Patients with diffuse drug-unresponsive HI manifest neurological impairment and neurobehavioral problems, even though surgically treated with a near-total pancreatectomy. Based on the analogies between HI and GLUT1 deficiency, both presenting with neuroglycopenia and lack of alternative cerebral energy sources, we administered a ketogenic diet (KD) in three drug-unresponsive GCK-HI patients with the aim of preserving neurodevelopment and avoiding the need of a near-total pancreatectomy. They presented recurrent symptomatic hypoglycemia, intellectual disability and refractory epilepsy. Patients were treated with classical KD for 79, 27 and 18 months, respectively. RESULTS: All patients became asymptomatic in a few days and showed an important improvement of the alert state. Epilepsy disappeared and no appearance of novel hypoglycemic lesions was detected with a brain MRI. Cognitive and adaptive abilities rapidly improved and normalized. IQ rose significantly from 81 to 111 (p = 0.04) in patient 1, from 82 vs 95 (p = 0.04) in patient 2, from 60 to 90 (p = 0.04) in patient 3. CONCLUSIONS: We demonstrated the safety and efficacy of KD in the treatment of drug-unresponsive GCK-HI at a short and long-term. The neuroprotective effects of KD determined the recovery from epilepsy and intellectual disabilities and averted the need of a near-total pancreatectomy. All patients and their families reported an improvement of physical and psychosocial well-being, with a substantial improvement of their quality of life. These results might change the course and the quality of life of these patients and their families, having a relevant impact on human lives. Therefore, KD might be considered the elective treatment in unresponsive forms of GCK-HI.

Hereditary spastic paraplegia is a novel phenotype for germline de novo ATP1A1 mutation.

Dominant mutations in ATP1A1, encoding the alpha-1 isoform of the Na+ /K+ -ATPase, have been recently reported to cause an axonal to intermediate type of Charcot-Marie-Tooth disease (ie, CMT2DD) and a syndrome with hypomagnesemia, intractable seizures and severe intellectual disability. Here, we describe the first case of hereditary spastic paraplegia (HSP) caused by a novel de novo (p.L337P) variant in ATP1A1. We provide evidence for the causative role of this variant with functional and homology modeling studies. This finding expands the phenotypic spectrum of the ATP1A1-related disorders, adds a piece to the larger genetic puzzle of HSP, and increases knowledge on the molecular mechanisms underlying inherited axonopathies (ie, CMT and HSP).

Neurobehavioral features in individuals with Kabuki syndrome.

BACKGROUND: Kabuki syndrome (KS) is a disorder characterized by multiple congenital anomalies affecting development and function of multiple systems. Over the years, researchers have attempted to characterize the neurobehavioral phenotype of KS in cohorts of patients enrolled on the basis of clinical assessment. The availability of molecular testing now allows for recruitment of patients with confirmed KS due to KMT2D and KDM6A. METHODS: The aims of the present study were to investigate the neuropsychological and behavioral profiles of individuals with molecularly confirmed diagnosis of KS, and determine the extent of heterogeneity occurring in these profiles between individuals with clinical diagnosis of KS with and without mutations in KMT2D. We also described performance of our cohort in any neuropsychological domain investigated. RESULTS: We documented a marked variation in the neuropsychological profile of subjects with clinical diagnosis of KS, even though a relatively homogeneous impairment in linguistic domains and motor skills was observed. No significant difference occurred between mutation-positive and mutation-negative groups. Phonological disorders and oromotor dysfunctions were also found, and adaptive functioning was characterized by low performance in daily living and in motor domain. CONCLUSION: The present study allowed identification of a distinctive neurobehavioral profile in a cohort of individuals affected by KS with or without molecularly confirmed diagnosis. These findings are expected to help clinicians define more accurately targeted protocols for individualized intervention.

Clinical and Neurobehavioral Features of Three Novel Kabuki Syndrome Patients with Mosaic KMT2D Mutations and a Review of Literature.

Kabuki syndrome (KS) is a rare disorder characterized by multiple congenital anomalies and variable intellectual disability caused by mutations in KMT2D/MLL2 and KDM6A/UTX, two interacting chromatin modifier responsible respectively for 56-75% and 5-8% of the cases. To date, three KS patients with mosaic KMT2D deletions in blood lymphocytes have been described. We report on three additional subjects displaying KMT2D gene mosaics including one in which a single nucleotide change results in a new frameshift mutation (p.L1199HfsX7), and two with already-known nonsense mutations (p.R4484X and p.R5021X). Consistent with previously published cases, mosaic KMT2D mutations may result in mild KS facial dysmorphisms and clinical and neurobehavioral features, suggesting that these characteristics could represent the handles for genetic testing of individuals with slight KS-like traits.

Cognitive, adaptive, and behavioral features in Joubert syndrome.

Joubert syndrome (JS) is a recessive neurodevelopmental disorder characterized by a distinctive cerebellar and brainstem malformation recognizable on brain imaging, the so-called molar tooth sign. The full spectrum of cognitive and behavioral phenotypes typical of JS is still far from being elucidated. The aim of this multicentric study was to define the clinical phenotype and neurobehavioral features of a large cohort of subjects with a neuroradiologically confirmed diagnosis of JS. Fifty-four patients aged 10 months to 29 years were enrolled. Each patient underwent a neurological evaluation as well as psychiatric and neuropsychological assessments. Global cognitive functioning was remarkably variable with Full IQ/General Quotient ranging from 32 to 129. Communication skills appeared relatively preserved with respect to both Daily Living and Socialization abilities. The motor domain was the area of greatest vulnerability, with a negative impact on personal care, social, and academic skills. Most children did not show maladaptive behaviors consistent with a psychiatric diagnosis but approximately 40% of them presented emotional and behavioral problems. We conclude that intellectual disability remains a hallmark but cannot be considered a mandatory diagnostic criterion of JS. Despite the high variability in the phenotypic spectrum and the extent of multiorgan involvement, nearly one quarter of JS patients had a favorable long-term outcome with borderline cognitive deficit or even normal cognition. Most of JS population also showed relatively preserved communication skills and overall discrete behavioral functioning in everyday life, independently from the presence and/or level of intellectual disability. © 2016 Wiley Periodicals, Inc.

A Novel Mutation in RPL10 (Ribosomal Protein L10) Causes X-Linked Intellectual Disability, Cerebellar Hypoplasia, and Spondylo-Epiphyseal Dysplasia.

RPL10 encodes ribosomal protein L10 (uL16), a highly conserved multifunctional component of the large ribosomal subunit, involved in ribosome biogenesis and function. Using X-exome resequencing, we identified a novel missense mutation (c.191C>T; p.(A64V)) in the N-terminal domain of the protein, in a family with two affected cousins presenting with X-linked intellectual disability, cerebellar hypoplasia, and spondylo-epiphyseal dysplasia (SED). We assessed the impact of the mutation on the translational capacity of the cell using yeast as model system. The mutation generates a functional ribosomal protein, able to complement the translational defects of a conditional lethal mutation of yeast rpl10. However, unlike previously reported mutations, this novel RPL10 missense mutation results in an increase in the actively translating ribosome population. Our results expand the mutational and clinical spectrum of RPL10 identifying a new genetic cause of SED and highlight the emerging role of ribosomal proteins in the pathogenesis of neurodevelopmental disorders.

Behavioral phenotype in Costello syndrome with atypical mutation: a case report.

Costello syndrome (CS) is a rare genetic disorder caused, in the majority of cases, by germline missense HRAS mutations affecting Gly(12) promoting enhanced signaling through the MAPK and PI3K-AKT signaling cascades. In general, the cognitive profile in CS is characterized by intellectual disability ranging from mild to severe impairment. The first published descriptions of behavior in CS children underlined the presence of irritability and shyness at younger ages with sociable personality and good empathic skills after 4-5 years of age, however some recent studies have reported autistic traits. We report on a 7-year-old boy heterozygous for a rare duplication of codon 37 (p.E37dup) in HRAS, manifesting impaired social interaction and non-verbal communication and with circumscribed interests. These additional features improve phenotype delineation in individuals with rare HRAS mutations, facilitating the development of specific behavioral treatments which could lead to improvement in cases of autism spectrum disorder.

Behavioral profile in RASopathies.

Here, we describe neurobehavioral features in patients with RASopathies (i.e., Noonan syndrome, LEOPARD syndrome, Costello syndrome, and cardiofaciocutaneous syndrome), developmental disorders caused by mutations in genes coding transducers participating in the RAS-MAPK signaling cascade. Parents of 70 individuals with a RASopathy were asked to fill out the following questionnaires: Child Behavior Checklist (CBCL), Social Communication Questionnaire version lifetime (SCQ-L), and Modified Checklist for Autism in toddlers (M-CHAT). Data analysis indicated high rates of internalizing (37%) and externalizing problems (31%) on CBCL. Scores over the cut-off were documented in 64% of patients with cardiofaciocutaneous syndrome, 44% with Costello syndrome, and 12% with Noonan syndrome on SCQ-L/M-CHAT. Our findings indicate that mutations promoting dysregulation of the RAS-MAPK cascade mark an increased psychopathological risk and highlight that autistic-like behavior could be underdiagnosed in patients with RASopathies.

Neurobehavioral phenotype observed in KBG syndrome caused by ANKRD11 mutations.

KBG syndrome is a rare disease characterized by typical facial dysmorphism, macrodontia of upper central incisors, skeletal abnormalities, and developmental delay. Recently, mutations in ANKRD11 gene have been identified in a subset of patients with KBG syndrome, while a contiguous gene deletion syndrome involving 16q24.3 region (including ANKRD11) was delineated in patients with facial dysmorphism, autism, intellectual disability, and brain abnormalities. Although numerous evidences point to a central causative role of ANKRD11 in the neurologic features of these patients, their neurocognitive and behavior phenotypes are still poorly characterized. Herein, we report the complete neurological and psychiatric features observed in two patients with KBG syndrome due to ANKRD11 mutations. Both patients show intellectual disabilities, severe impairment in communication skills, deficits in several aspects of executive functions and working memory and anxious traits. Their features are compared with those of previously reported patients with KBG syndrome aiding in the delineation of neurocognitive phenotype associated to ANKRD11 mutations.

Increased sleep spindle activity in patients with Costello syndrome (HRAS gene mutation).

Costello syndrome is a congenital disorder because of HRAS gene mutation, frequently associated with neurologic impairment and sleep disorders. The aims of the study were to evaluate the sleep EEG, and particularly the sleep spindles, in a population of patients with Costello syndrome and to compare them with those characterizing unaffected subjects. Eleven subjects (5 men and 6 women) with Costello syndrome were included in the study; age ranged between 18 months and 31 years (mean, 9.6 ± 9.4 years). The diagnosis was posed on the basis of established clinical criteria and confirmed molecularly. Sleep EEG was studied by means of full-night, laboratory-based video-polysomnography, performed overnight, during hospitalization. Sleep activity was quantified by means of power spectral analysis. Patients heterozygous for an HRAS mutation exhibited increased EEG power in 12- to 15-Hz activity band compared with age-matched control subjects. In conclusion, the authors observed a consistent increase in the amplitude of cortical sleep spindles in all our subjects with an HRAS mutation. These "giant" spindles were not associated with any evidence of structural damage of the cortex or the thalami and should be considered as phenotypic feature of sleep EEG activity in Costello syndrome because of HRAS mutation.

Cognitive profile of disorders associated with dysregulation of the RAS/MAPK signaling cascade.

Mutations in genes coding for transducers participating in the RAS/MAPK pathway have been identified as the molecular cause underlying a group of clinically related developmental disorders with cognitive deficits of variable severity. To determine the spectrum of cognitive defects associated with dysregulation of this signal cascade, we studied the profile of cognitive abilities in patients with mutations affecting the PTPN11, SOS1, HRAS, KRAS, BRAF, RAF1, and MEK1 genes and phenotype-genotype correlations. Our findings support the observation that heterogeneity in cognitive abilities can be at least partially ascribed to the individual affected genes and type of mutation involved. While mutations affecting transducers upstream of RAS were less frequently associated with mental retardation, mutations in downstream components of the pathway were generally associated with a more severe cognitive impairment. Among patients with a heterozygous PTPN11 mutation, the T468M substitution was associated with a mean IQ significantly higher compared to that of individuals carrying the N308D change. Our study provides insights on the range of cognitive abilities in patients with gene mutations causing dysregulation of RAS signaling suggesting that the presence and severity of cognitive involvement can be predicted in part by the gene involved.