NGS study in a sicilian case series with a genetic diagnosis for Gerstmann-Sträussler-Scheinker syndrome (PRNP, p.P102L).

BACKGROUND: Gerstmann Sträussler Scheinker (GSS) is an inherited, invariably fatal prion disease. Like other human prion diseases, GSS is caused by missense mutations in the prion protein (PrP) gene (PRNP), and by the formation and overtime accumulation of the misfolded, pathogenic scrapie PrP (PrPSc). The first mutation identified in the PRNP gene, and the one blamed as the main cause of the disease, is c.C305T:p.P102L. METHODS AND RESULTS: The Sanger sequencing method was performed on the PRNP gene for the detection of c.C305T:p.P102L mutations in a cohort of 10 subjects; moreover, a study was carried out, using Next Generation Sequencing (NGS), by sequencing a group of genes related to amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), movement disorders and dementia which show a phenotypic profile similar to that of GSS. The results obtained from the study using NGS indicate the potential role of other genetic variants which could contribute to the various GSS phenotypes. CONCLUSIONS: In conclusion, we highlight the large clinical variability in subjects presenting with GSS and p.P102L, as well as the hypothesis that the mutation in PrP codon 102 alone is not sufficient to trigger the cardinal clinical signs of the disease; furthermore, we do not exclude the possibility that further genetic variants play a decisive role in the aspects of the various phenotypes with which GSS manifests itself.

Identification of a Novel FOXP1 Variant in a Patient with Hypotonia, Intellectual Disability, and Severe Speech Impairment.

The FOXP subfamily includes four different transcription factors: FOXP1, FOXP2, FOXP3, and FOXP4, all with important roles in regulating gene expression from early development through adulthood. Haploinsufficiency of FOXP1, due to deleterious variants (point mutations, copy number variants) disrupting the gene, leads to an emerging disorder known as "FOXP1 syndrome", mainly characterized by intellectual disability, language impairment, dysmorphic features, and multiple congenital abnormalities with or without autistic features in some affected individuals (MIM 613670). Here we describe a 10-year-old female patient, born to unrelated parents, showing hypotonia, intellectual disability, and severe language delay. Targeted resequencing analysis allowed us to identify a heterozygous de novo FOXP1 variant c.1030C>T, p.(Gln344Ter) classified as likely pathogenetic according to the American College of Medical Genetics and Genomics guidelines. To the best of our knowledge, our patient is the first to date to report carrying this stop mutation, which is, for this reason, useful for broadening the molecular spectrum of FOXP1 clinically relevant variants. In addition, our results highlight the utility of next-generation sequencing in establishing an etiological basis for heterogeneous conditions such as neurodevelopmental disorders and providing additional insight into the phenotypic features of FOXP1-related syndrome.

Growth hormone, gender and face shape in Prader-Willi syndrome.

Prader-Willi syndrome is a neurodevelopmental disorder resulting from the absence of expression of paternally expressed gene(s) in a highly imprinted region of chromosome 15q11-13. The physical phenotype includes evidence of growth retardation due to relative growth hormone deficiency, small hands and feet, a failure of normal secondary sexual development, and a facial appearance including narrow bifrontal diameter, almond-shaped palpebral fissures, narrow nasal root, and thin upper vermilion with downturned corners of the mouth. Anecdotally, the face of individuals with PWS receiving hGH treatment is said to "normalize." We used dense surface modelling and shape signature techniques to analyze 3D photogrammetric images of the faces of 72 affected and 388 unaffected individuals. We confirmed that adults with Prader-Willi syndrome who had never received human growth supplementation displayed known characteristic facial features. Facial growth was significantly reduced in these adults, especially in males. We demonstrated that following human growth hormone (hGH) supplementation, vertical facial growth of affected individuals falls within the normal range. However, lateral and periorbital face shape and nose shape differences in affected children who have received hGH therapy remain sufficiently strong to be significantly discriminating in comparisons with age-sex matched, unaffected individuals. Finally, we produced evidence that age at initiation and length of treatment with hGH do not appear to play a role in normalization or in consistent alteration of the face shape of affected individuals. This is the first study to provide objective shape analysis of craniofacial effects of hGH therapy in Prader-Willi syndrome.

Craniofacial characteristics of fragile X syndrome in mouse and man.

For a disorder as common as fragile X syndrome, the most common hereditary form of cognitive impairment, the facial features are relatively ill defined. An elongated face and prominent ears are the most commonly accepted dysmorphic hallmarks. We analysed 3D facial photographs of 51 males and 15 females with full FMR1 mutations and 9 females with a premutation using dense-surface modelling techniques and a new technique that forms a directed graph with normalized face shapes as nodes and edges linking those with closest dysmorphism. In addition to reconfirming known features, we confirmed the occurrence of some at an earlier age than previously recorded. We also identified as yet unrecorded facial characteristics such as reduced facial depth, hypoplasticity of the nasal bone-cartilage interface and narrow mid-facial width exaggerating ear prominence. As no consistent craniofacial abnormalities had been reported in animal models, we analysed micro-CT images of the fragile X mouse model. Results indicated altered dimensions in the mandible and both outer and inner skull, with the latter potentially reflecting differences in neuroanatomy. We extrapolated the mouse results to face shape differences of the human fragile X face.

Phenotypic spectrum of 20 novel patients with molecularly defined supernumerary marker chromosomes 15 and a review of the literature.

Supernumerary marker chromosomes (SMC) originating from chromosome 15 are the most common SMCs. They encompass clinically irrelevant SMC(15)s containing only heterochromatin and 15p material, and clinically relevant SMC(15)s that consist of both eu- and heterochromatic 15q material. On the basis of size, the clinically relevant SMC(15)s can be subdivided into type A, "large" asymmetric and type B, "small" symmetric SMC(15)s. Type B SMC(15)s contain the triplicated 15pter to BP3 (located at 26.5 Mb) region, while type A SMC(15)s consist of 15pter --> BP4(28.5 Mb)::BP5(30.5 Mb) --> 15pter. In this study, the clinical and molecular features of 18 patients with A and B SMC(15)s and two patients with a partial trisomy 15q were reviewed. Questionnaires (including Child Behavior Check Lists) were used to assess behavior and developmental features in more detail. The marker size and parental origin were determined by multiplex ligation-dependent probe amplification (MLPA). Based on the MLPA results, the majority of patients (14/18) had type A SMC(15)s. The phenotype observed did not show significant differences between types A and B SMC(15)s. A high prevalence of autistic-like behavior, attention problems, aggressive behavior, anxiety, and sleeping problems was reported. Motor and speech development varied extensively among the patients. An association was found between positive seizure history and degree of intellectual disability.

Jacobsen syndrome.

Jacobsen syndrome is a MCA/MR contiguous gene syndrome caused by partial deletion of the long arm of chromosome 11. To date, over 200 cases have been reported. The prevalence has been estimated at 1/100,000 births, with a female/male ratio 2:1. The most common clinical features include pre- and postnatal physical growth retardation, psychomotor retardation, and characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears). Abnormal platelet function, thrombocytopenia or pancytopenia are usually present at birth. Patients commonly have malformations of the heart, kidney, gastrointestinal tract, genitalia, central nervous system and skeleton. Ocular, hearing, immunological and hormonal problems may be also present. The deletion size ranges from approximately 7 to 20 Mb, with the proximal breakpoint within or telomeric to subband 11q23.3 and the deletion extending usually to the telomere. The deletion is de novo in 85% of reported cases, and in 15% of cases it results from an unbalanced segregation of a familial balanced translocation or from other chromosome rearrangements. In a minority of cases the breakpoint is at the FRA11B fragile site. Diagnosis is based on clinical findings (intellectual deficit, facial dysmorphic features and thrombocytopenia) and confirmed by cytogenetics analysis. Differential diagnoses include Turner and Noonan syndromes, and acquired thrombocytopenia due to sepsis. Prenatal diagnosis of 11q deletion is possible by amniocentesis or chorionic villus sampling and cytogenetic analysis. Management is multi-disciplinary and requires evaluation by general pediatrician, pediatric cardiologist, neurologist, ophthalmologist. Auditory tests, blood tests, endocrine and immunological assessment and follow-up should be offered to all patients. Cardiac malformations can be very severe and require heart surgery in the neonatal period. Newborns with Jacobsen syndrome may have difficulties in feeding and tube feeding may be necessary. Special attention should be devoted due to hematological problems. About 20% of children die during the first two years of life, most commonly related to complications from congenital heart disease, and less commonly from bleeding. For patients who survive the neonatal period and infancy, the life expectancy remains unknown.

Do visuospatial and constructional disturbances differentiate frontal variant of frontotemporal dementia and Alzheimer's disease? an experimental study of a clinical belief.

BACKGROUND: In recent years several attempts have been made to distinguish frontotemporal dementia (FTD) from Alzheimer's disease (AD) on neuropsychological grounds; in particular, it has been suggested that FTD patients show spared spatial abilities with respect to AD patients. OBJECTIVE: We aimed at verifying whether patients with the frontal variant of frontotemporal dementia (fv-FTD) and AD patients perform differently on visuospatial and constructional tasks. METHODS: We assessed a wide range of visuospatial abilities and provided a qualitative analysis of constructional performances in 14 fv-FTD patients and 11 AD patients, matched for general cognitive abilities. RESULTS: The two groups of patients achieved similar scores on two copying tasks, presented similar drawing procedures in copying Rey complex figure and made a similar quantitative and qualitative pattern of errors in copying simple geometrical drawings. Moreover, no significant difference was found between fv-FTD and AD patients on a specific battery for visuospatial abilities. CONCLUSIONS: Our data and a review of the literature suggest that basic visuospatial and constructional skills cannot be taken as a reliable diagnostic criterion for distinguishing fv-FTD and AD at a mild to moderate disease stage and that the clinical belief of spared spatial abilities in fv-FTD has to be referred to the lack of topographic disorientation in comparison to AD.