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.

The Italian National Survey for Prader-Willi syndrome: an epidemiologic study.

Twenty-five medical centers and the Prader-Willi Syndrome (PWS) Association collaborated on a study which attempted to identify all people with genetically confirmed diagnosis of PWS living in Italy. Investigators of the participating centers contacted PWS subjects and/or their family, filled in a specially developed form with the required data and forwarded this information by email. The study identified 425 subjects (209 males and 216 females, between the ages of 0.4-46.7). Two hundred thirty-eight patients had del15, 104 had UPD15, 4 demonstrated a translocation affecting chromosome 15 and 79 showed a positive methylation test. There were fewer subjects found over the age of 35, probably due to the low rate of identification of older PWS patients as well as the high mortality rate. There were a greater number of male children and adolescents with PWS whilst, amongst adults, there were more females. As expected, the majority of subjects with PWS were obese, especially in adult life. Nevertheless, it is noteworthy that 26% of patients aged between 6 and 17 were normal weight. A total of 212 subjects had received GH treatment, of which 141 were still receiving therapy, while the remaining 71 had stopped. In children and adolescents (233 cases), 89 subjects had never undergone GH therapy. Eighteen PWS patients had died in the past 20 years. Obesity-related cardiovascular and respiratory diseases were the cause of death, both during childhood and after 18 years of age. Three children died suddenly whilst undergoing GH therapy. Respiratory infection and cardiac illness were the causes of death in two cases. There was no definitive cause of death found in the third case. Overall, there was no increase in number of deaths during GH treatment, suggesting that GH administration in patients with PWS, as a group, does not increase the risk of death.

Identification and molecular modelling of a novel familial mutation in the SRY gene implicated in the pure gonadal dysgenesis.

SRY gene is responsible for initiating male sexual differentiation. The protein encoded by SRY contains a homeobox (HMG) domain, which is a DNA-binding domain. Mutations of the SRY gene are reported to be associated with XY pure gonadal dysgenesis. The majority of these are de novo mutations affecting only one individual in a family. Only a small subset of mutations is shared between the father and one or more of his children. Most of these familial mutations are localized within the HMG box and only two are at the N-terminal domain of the SRY protein. Herein, we describe a young girl with pure gonadal dysgenesis and her father carrying a novel familial mutation in the SRY gene at codon number 3. This mutation is resulting in a serine (S) to leucine (L) substitution. The secondary structure of the SRY protein was carried out by protein modelling studies. This analysis suggests, with high possibility, that the N-terminal domain of the SRY protein, where we found the mutation, could form an alpha-helix from amino acid in position 2 to amino acid in position 13. The secondary structure prediction and the chemical properties of serine to leucine substitution stands for a potential disruption of this N-terminal alpha-helix in the SRY protein. This mutation could have some role in impeding the normal function of the SRY protein.

Endocrine and growth features in childhood craniopharyngioma: a mono-institutional study.

OBJECTIVE: To evaluate growth and endocrine features in children with craniopharyngioma who were treated and followed up by a single institution between 1976 and 2004. PATIENTS: The records of 32 children, 18 males and 14 females, were evaluated. The mean follow-up period was 6.3 years. RESULTS: At presentation, the most common symptoms were headache, nausea and vomiting, visual impairment, and neurological changes. Some patients presented signs or symptoms of isolated or combined endocrine disorder (five polyuria and polydipsia, five growth failure, two precocious puberty, eight obesity or overweight). After tumour treatment, multiple pituitary hormonal deficiencies, especially growth hormone (GH) deficit (GHD) were found and required hormonal replacement therapy. Eight children grew normally without GH despite GHD. Hypothalamic involvement was observed in ten patients; obesity was frequent and was often associated with hyperinsulinism and hyperphagia. CONCLUSION: Anterior and posterior pituitary deficiencies following surgery are present in all patients. The growth pattern is heterogeneous.

Parental origin of Gsalpha mutations in the McCune-Albright syndrome and in isolated endocrine tumors.

Activating mutations of the Gsalpha gene are detected in different endocrine tumors, such as GH-secreting adenomas and toxic thyroid adenomas, and in hyperfunctioning glands from patients with McCune-Albright syndrome (MAS). There is increasing evidence that the Gsalpha gene is subjected to imprinting control and that Gsalpha imprinting plays a key role in the pathogenesis of different human diseases. The aim of this study was to investigate the presence of a parent specificity of Gsalpha mutations in 10 patients affected with MAS and 12 isolated tumors (10 GH-secreting adenomas, one toxic thyroid adenoma, and one hyperfunctioning adrenal adenoma). The parental origin of Gsalpha mutations was assessed by evaluating NESP55 and exon 1A transcripts, which are monoallelically expressed from the maternal and paternal alleles, respectively. By this approach, we demonstrated that in isolated GH-secreting adenomas, as well as in MAS patients with acromegaly, Gsalpha mutations were on the maternal allele. By contrast, the involvement of other endocrine organs in MAS patients was not associated with a particular parent specificity, as precocious puberty and hyperthyroidism were present in patients with mutations on either the maternal or the paternal allele. Moreover, isolated hyperfunctioning thyroid and adrenal adenomas displayed the mutation on the maternal and paternal alleles, respectively. These data confirm the importance of Gsalpha imprinting in the pituitary gland and point out the high degree of tissue specificity of this phenomenon.

Different inactivating mutations of the mineralocorticoid receptor in fourteen families affected by type I pseudohypoaldosteronism.

We have analyzed the human mineralocorticoid receptor (hMR) gene in 14 families with autosomal dominant or sporadic pseudohypoaldosteronism (PHA1), a rare form of mineralocorticoid resistance characterized by neonatal renal salt wasting and failure to thrive. Six heterozygous mutations were detected. Two frameshift mutations in exon 2 (insT1354, del8bp537) and one nonsense mutation in exon 4 (C2157A, Cys645stop) generate truncated proteins due to premature stop codons. Three missense mutations (G633R, Q776R, L979P) differently affect hMR function. The DNA binding domain mutant R633 exhibits reduced maximal transactivation, although its binding characteristics and ED(50) of transactivation are comparable with wild-type hMR. Ligand binding domain mutants R776 and P979 present reduced or absent aldosterone binding, respectively, which is associated with reduced or absent ligand-dependent transactivation capacity. Finally, P979 possesses a transdominant negative effect on wild-type hMR activity, whereas mutations G633R and Q776R probably result in haploinsufficiency in PHA1 patients. We conclude that hMR mutations are a common feature of autosomal dominant PHA1, being found in 70% of our familial cases. Their absence in some families underscores the importance of an extensive investigation of the hMR gene and the role of precise diagnostic procedures to allow for identification of other genes potentially involved in the disease.

Auxological and metabolic study in small for gestational age children during 2 years follow-up.

OBJECTIVE: To compare auxological and metabolic status of preterm (PT) and fullterm (FT) small for gestational age (SGA) babies from birth until age 2 years and to study the role of intrauterine growth retardation (IUGR) in auxological and metabolic outcome in SGA babies. METHODS: We enrolled 44 SGA babies (22 FTs, 22 PTs) followed up six monthly. Anthropometric and metabolic measurements (fasting glucose, basal insulin level, total-cholesterol, triglycerides) were performed. HOMA-IR was selected to assess insulin sensitivity. RESULTS: Both FTs and PTs from birth to age 6 months showed a significant increase in weight and length; the weight gain decreased from 6 to 12 months only in PTs. At 24 months, we observed catch-up growth in 90% of FTs and 87% of PTs. Insulinemia and HOMA-IR decreased from birth to 24 months, in particular between 6 and 12 months. PTs SGA with IUGR were significantly smaller than FTs SGA without IUGR (p = 0.01) and showed a lower length growth velocity. Moreover they showed also higher insulin levels and HOMA-IR at birth; these values decreased at 12 and 24 months. CONCLUSIONS: Our study showed no significant difference between PTs and FTs SGA in auxological and metabolic parameters. However, prematurity with IUGR proved to be a significant factor that should be considered in the timing of auxological follow-up of SGA subjects.

Effect of environment on growth: auxological and hormonal parameters in African and Italian children.

OBJECTIVE: Genetic factors are the most important determinant of final height in developed countries, while in underprivileged countries food intake is crucial. Nutrients, in turn, may importantly affect IGF-IGFBP system which is a critical regulator of growth. The aim of this study was to evaluate the influence of nutrition on IGF system components, as well as on growth by comparing these variables in two selected populations of children living either in poor or in privileged environmental conditions. DESIGN: Height and weight were recorded in 38 normal African children, living in a Catholique Mission in Ivory Coast, and in 93 normal Italian children. IGF-I, IGF-II, IGFBP-3 and ALS were evaluated in all subjects. RESULTS: A normal height in spite of markedly reduced IGF-I, IGFBP-3, ALS and BMI was observed in African children, while the ratio IGF-I/IGFBP-3 was comparable in the two populations. IGF-II was slightly but significantly higher in Africans than in Italians. CONCLUSIONS: In Africans a suboptimal nutritional condition may produce a dramatic reduction of IGF-I, ALS and IGFBP-3, although the final height results minimally affected. This suggests that only a small fraction of the circulating IGF-I is sufficient for growth and confirms what has been reported on liver IGF-I-deficient and ALS knock-out mice. The secular statural trend observed in developed countries is probably due to the increase of IGF-I consequent to the improved nutritional conditions.

Influence of age, gender, and glucose tolerance on fasting and fed acylated ghrelin in Prader Willi syndrome.

BACKGROUND & AIMS: Prader Willi syndrome (PWS) is a genetic syndrome characterized by hyperphagia, morbid obesity, relative hypoinsulinemia and normal insulin sensitivity. PWS presents higher total (TG) and acylated ghrelin (AG) levels. The cause of this increase as well as the modulation of ghrelin secretion in fasting and feeding in relation to other metabolic parameters and glucose tolerance in PWS is largely unknown. METHODS: We studied TG and AG at fasting in PWS children (14) and adults (18). We also studied TG and AG response to a mixed standardized light breakfast (SLB) in PWS adults without (AD-GT) and with glucose intolerance (AD-GI) at OGTT. RESULTS: TG and AG were higher in children than in adults (p<0.05). AG was higher in adult males (p<0.001). Fasting AG and AG/TG ratio were lower in AD-GI than in AD-GT (p<0.05). TG, but not AG, decreased in AD-GT (p<0.006), whereas AG, but not TG, increased in AD-GI (p<0.03) post-SLB. Fasting TG and AG were negatively predicted by fasting insulin (p<0.05). Post-SLB AG was positively predicted by glucose during OGTT (p<0.04). CONCLUSIONS: Fasting and post-meal AG levels are influenced by glucose tolerance in PWS, suggesting that AG derangement might have a role in the development of glucose intolerance.

Differences in size at birth are determined by differences in growth velocity during early prenatal life.

Physiologic interindividual differences in neonatal size are traditionally thought of as determined by differences in fetal growth occurring only in the second half of pregnancy. Whether possible differences in early intrauterine growth velocity are the effect of random growth fluctuations or may affect size at birth is still debated. This article aims at evaluating to what extent differences in neonatal size are accounted for by differences in fetal growth velocity. We analyzed the fetal growth of 130 healthy singletons for whom head (HC) and abdomen (AC) circumferences and femur diaphysis length (FDL) longitudinal profiles were available, together with the measures of weight (BW), length (BL), and head circumference (BHC) at birth. Individual profiles were fitted with ad-hoc models. Neonatal traits were transformed into standard deviation scores (SDS). Neonates in the upper third of BW-SDS distribution (3618+/-43 g, mean+/-SEM) had, at 22 wk of gestational age, AC growth velocity higher by 0.55+/-0.10 mm/wk than those in the lower third (2902+/-36 g). Neonates in the upper third of BL-SDS distribution (51.7+/-0.21 cm) had, at 20 wk, FDL growth velocity higher by 0.11+/-0.05 mm/wk than those in the lower third (48.2+/-0.18 cm). Neonates in the upper third of BHC-SDS distribution (35.7+/-0.13 cm) had, at 18 wk, HC growth velocity higher by 0.57+/-0.20 mm/wk than those in the lower third (33.3+/-0.11 cm). The differences in growth velocity remain constant throughout the second and third trimester for AC, and tend to vanish in the third trimester for HC and FDL. The differences in fetal growth velocity, which in our study were observed as early as mo 4, suggest that the genetic component plays an important role in fetal growth and is precociously expressed.