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Micale L.,IRCCS Casa Sollievo Della Sofferenza Hospital | Augello B.,IRCCS Casa Sollievo Della Sofferenza Hospital | Maffeo C.,IRCCS Casa Sollievo Della Sofferenza Hospital | Selicorni A.,University of Milan Bicocca | And 37 more authors.
Human Mutation | Year: 2014

Kabuki syndrome (KS) is a multiple congenital anomalies syndrome characterized by characteristic facial features and varying degrees of mental retardation, caused by mutations in KMT2D/MLL2 and KDM6A/UTX genes. In this study, we performed a mutational screening on 303 Kabuki patients by direct sequencing, MLPA, and quantitative PCR identifying 133 KMT2D, 62 never described before, and four KDM6A mutations, three of them are novel. We found that a number of KMT2D truncating mutations result in mRNA degradation through the nonsense-mediated mRNA decay, contributing to protein haploinsufficiency. Furthermore, we demonstrated that the reduction of KMT2D protein level in patients' lymphoblastoid and skin fibroblast cell lines carrying KMT2D-truncating mutations affects the expression levels of known KMT2D target genes. Finally, we hypothesized that the KS patients may benefit from a readthrough therapy to restore physiological levels of KMT2D and KDM6A proteins. To assess this, we performed a proof-of-principle study on 14 KMT2D and two KDM6A nonsense mutations using specific compounds that mediate translational readthrough and thereby stimulate the re-expression of full-length functional proteins. Our experimental data showed that both KMT2D and KDM6A nonsense mutations displayed high levels of readthrough in response to gentamicin treatment, paving the way to further studies aimed at eventually treating some Kabuki patients with readthrough inducers. In this report, we have expanded the spectrum of mutations of KMT2D and KDM6A genes by analysing our cohort of 303 Kabuki patients by direct sequencing, MLPA and quantitative PCR. Based on KMT2D biological role, we designed functional studies that highlighted the haploinsufficiency of KMT2D as one of the mechanisms underlying the pathogenesis of the disease. Moreover, we provided the first preliminary proof-of-concept that occurring nonsense mutations in KMT2D and KDM6A can be effectively suppressed and the functional endogenous protein level and biological activity of KMT2D and KDM6A proteins restored. © 2014 The Authors.

Bukvic N.,Uoc Laboratorio Of Genetica Medica | Varvara D.,University of Bari | Rossi C.,Uo Laboratorio Of Genetica Medica | Faienza M.F.,University of Bari | And 2 more authors.
Genetika | Year: 2015

Noonan syndrome (NS) is an autosomal dominant disorder, characterized by variable expressivity of clinical features such as: Postnatal growth reduction, congenital heart disease, characteristic facial dysmorphisms and development delay. In ~75% of all NS cases, germline mutations involving RAS-MAPK signaling pathway genes (PTPN11, SOS1, RAF1, KRAS, NRAS, BRAF, SHOC2, MEK1, CBL) are causative. We reported a case of 13-year-old girl [born at 36w by CS (BW 3250 g (~95°), BL 48 cm (~75°)] referred for genetic counseling due to growth retardation, facial dysmorphisms, development delay and learning disability. After birth she presented frequent vomiting, with failure to thrive and at 5 months of age underwent surgery for intestinal malrotation. Because of short stature, Growth Hormone (GH) therapy have been introduced at age of 3yrs up to 11yrs. Negative molecular testing for PTPN11 and SOS1 genes, normal female karyotype and aCGH analysis were observed. Objective examination: H 138 cm, (< 3°); W 33 kg, (<3°), no menarche, hypertelorism, eyelids ptosis with down slanting palpebral fissures, low-set and posteriorly rotated ears, high-arched palate, micrognathia, short and webbed neck, low hairline at the back of the neck, pectus excavatum, prominent scoliosis, joint hyperextensibility, bilateral pes planus and mitral valve prolapse disclosed by US. Phenotype of our patient was suggestive to NS, thus further mutational screening has been requested. Missense mutation in exon 2 of KRAS gene (c.40G > A; p.Val14Ile) has been identified. Even though KRAS mutations are usually associated with NS severe phenotype with cardiac involvement (hypertrophic cardiomyopathy), this finding is not present in our patient.

Baroncelli G.I.,UO Pediatria I | Toschi B.,Uo Laboratorio Of Genetica Medica | Cinquanta L.,UOC Pediatria | Manfredi P.,Presidio | And 4 more authors.
Medico e Bambino | Year: 2013

The term "vitamin D-resistant rickets" was used to describe a clinical condition which was indistinguishable from the common rickets except that the signs occurred in spite of adequate vitamin D treatment. Recent studies showed that vitamin D-resistant rickets is due to genetic mutations of some enzymes involved in vitamin D activation, metabolism or action. This may explain why vitamin D treatment is not able to cure patients affected by these forms of rickets. Indeed, vitamin D metabolites (calcitriol, alfacalcidol) associated with calcium or phosphate salts according to the pathogenesis of the disease are the most effective treatments for patients affected by rickets due to genetic mutations. The evidence of a genetic mutation in a patient with rickets is crucial not only for a correct diagnosis and treatment, but also for prognosis.

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