Significant Improvement of Clinical Symptoms, Bone Lesions, and Bone Turnover after Long-Term Zoledronic Acid Treatment in Patients with a Severe Form of Camurati-Engelmann Disease.

Camurati-Engelmann disease (CED) is an ultrarare autosomal dominant bone dysplasia. Cortical thickening of the diaphyses of the long bones with narrowing of the medullary cavity are associated with bone pain, waddling gait, muscular weakness, easy fatigability, and a marfanoid body habitus. There is no specific treatment for CED. Nonsteroidal anti-inflammatory drugs or glucocorticoids are ineffective in improving bone lesions. A family with a mild to severe form of CED is described. Two patients received long-term bisphosphonate treatment: the 19-year-old female proband was treated with zoledronic acid for 2.2 years; the 4-year-old male proband was treated with neridronic acid for 16 months and with zoledronic acid for an additional 18 months. In both probands, zoledronic acid treatment significantly improved the clinical symptoms, bone lesions, ambulation, and body habitus. Before treatment, both probands showed a marked increase in serum levels of osteocalcin, procollagen type I N-terminal propeptide, and cross-linked carboxyterminal telopeptide of type I collagen, reflecting an increased bone turnover. Bone marker levels returned to their normal values during treatment. Zoledronic acid treatment may be an important therapeutic option in patients with severe CED. Biochemical markers of bone turnover could be considered as surrogate indexes of CED activity.

Growth in Boys with 45,X/46,XY Mosaicism: Effect of Growth Hormone Treatment on Statural Growth.

45,X/46,XY mosaicism is a rare sex chromosome disorder of sex development. Short stature is a main feature of boys with this condition. Different causes likely contribute to growth impairment. Growth hormone (GH) has been administered to treat short stature in boys with 45,X/46,XY mosaicism, but conflicting data are available. Here, spontaneous growth patterns as well as short- and long-term follow-up studies during GH therapy in these patients are reviewed. Short- and mid-term data showed an improvement of the growth pattern in GH-treated boys, mainly when hormonal therapy was started early, while long-term follow-up demonstrated similar adult heights in GH-treated and untreated patients. Individual biological factors (e.g. different chromosome constitution, different mosaicism among various tissues, impaired pubertal growth spurt), non-homogeneous GH doses and different ages at start of therapy may contribute to the variable results. Thus, early GH therapy at pharmacological doses may improve the growth pattern of short boys with 45,X/46,XY mosaicism, but data on adult height are disappointing. Evaluation of larger patient samples treated by homogeneous doses and long-term follow-up studies assessing adult height and safety are needed to reach definitive conclusions on GH therapy in boys with 45,X/46,XY mosaicism.

625 kb microduplication at Xp22.12 including RPS6KA3 in a child with mild intellectual disability.

Here, we report on a patient with a 625 kb duplication in Xp22.12, detected by array comparative genomic hybridization (CGH). The duplicated region contains only one gene, RPS6KA3, that results in partial duplication. The same duplication was present in his mother and his maternal uncle. This partial duplication inhibits the RPS6KA3 expression, mimicking the effect of loss-of-function mutations associated with Coffin-Lowry syndrome (CLS). The phenotype of the patient here presented is not fully evocative of this syndrome because he does not present some of the facial, digital and skeletal abnormalities that are considered the main diagnostic features of CLS. This case is one of the few examples where RPS6KA3 mutations are associated with a non-specific X-linked mental retardation.

Molecular analysis, pathogenic mechanisms, and readthrough therapy on a large cohort of Kabuki syndrome patients.

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.

Mutation spectrum of MLL2 in a cohort of Kabuki syndrome patients.

BACKGROUND: Kabuki syndrome (Niikawa-Kuroki syndrome) is a rare, multiple congenital anomalies/mental retardation syndrome characterized by a peculiar face, short stature, skeletal, visceral and dermatoglyphic abnormalities, cardiac anomalies, and immunological defects. Recently mutations in the histone methyl transferase MLL2 gene have been identified as its underlying cause. METHODS: Genomic DNAs were extracted from 62 index patients clinically diagnosed as affected by Kabuki syndrome. Sanger sequencing was performed to analyze the whole coding region of the MLL2 gene including intron-exon junctions. The putative causal and possible functional effect of each nucleotide variant identified was estimated by in silico prediction tools. RESULTS: We identified 45 patients with MLL2 nucleotide variants. 38 out of the 42 variants were never described before. Consistently with previous reports, the majority are nonsense or frameshift mutations predicted to generate a truncated polypeptide. We also identified 3 indel, 7 missense and 3 splice site. CONCLUSIONS: This study emphasizes the relevance of mutational screening of the MLL2 gene among patients diagnosed with Kabuki syndrome. The identification of a large spectrum of MLL2 mutations possibly offers the opportunity to improve the actual knowledge on the clinical basis of this multiple congenital anomalies/mental retardation syndrome, design functional studies to understand the molecular mechanisms underlying this disease, establish genotype-phenotype correlations and improve clinical management.

Endometrial cancer and somatic G>T KRAS transversion in patients with constitutional MUTYH biallelic mutations.

MUTYH-associated polyposis (MAP) is an autosomal recessive condition predisposing to colorectal cancer, caused by constitutional biallelic mutations in the base excision repair (BER) gene MUTYH. Colorectal tumours from MAP patients display an excess of somatic G>T mutations in the APC and KRAS genes due to defective BER function. To date, few extracolonic manifestations have been observed in MAP patients, and the clinical spectrum of this condition is not yet fully established. Recently, one patient with a diagnosis of endometrial cancer and biallelic MUTYH mutations has been described. We here report on two additional unrelated MAP patients with biallelic MUTYH germline mutations who developed endometrioid endometrial carcinoma. The endometrial tumours were evaluated for PTEN, PIK3CA, KRAS, BRAF and CTNNB1 mutations. A G>T transversion at codon 12 of the KRAS gene was observed in one tumour. A single 1bp frameshift deletion of PTEN was observed in the same sample. Overall, these findings suggest that endometrial carcinoma is a phenotypic manifestations of MAP and that inefficient repair of oxidative damage can be involved in its pathogenesis.