382 research outputs found
Reference intervals for acetylated fetal hemoglobin in healthy newborns
The acetylated fetal hemoglobin (AcHbF)
derives from an enzyme-mediated post-translational
modification occurring on the N-terminal
glycine residues of g-chains. At present,
no established data are available on reference
intervals for AcHbF in newborns. A total of 92
healthy infants, with gestational age between
37 and 41 weeks were selected for the establishment
of AcHbF reference intervals. Blood
samples were collected by heel pricking, when
collecting routine neonatal screening, and the
hemoglobin pattern was analyzed by high-performance
liquid chromatography. AcHbF
results were then normalized for HbF content
in order to account for differences in hemoglobin
switch. No difference was found in AcHbF
values between genders (P=0.858). AcHbF
results were as follow: 12.8\ub10.8% (mean\ub1standard
deviation), reference interval: 11.3-14.3%.
This finding could facilitate further studies
aimed to assess the possible use of AcHbF, for
instance as a possible fetal metabolic biomarker
during pregnancy
Growth hormone therapy and respiratory disorders: Long-term follow-up in PWS children
Context: Adenotonsillar tissue hypertrophy and obstructive sleep apnea have been reported during short-term GH treatment in children with Prader-Willi syndrome (PWS). Objective: We conducted an observational study to evaluate the effects of long-term GH therapy on sleep-disordered breathing and adenotonsillar hypertrophy in children with PWS. Design: This was a longitudinal observational study. PatientsandMethods:Weevaluated 75 children with genetically confirmedPWS,ofwhom50 fulfilled the criteria and were admitted to our study. The patients were evaluated before treatment (t0), after 6 weeks (t1), after 6 months (t2), after 12 months (t3), and yearly (t4-t6) thereafter, for up to 4 years of GH therapy. The central apnea index, obstructive apnea hypopnea index (OAHI), respiratory disturbance index, and minimal blood oxygen saturation were evaluated overnight using polysomnography. We evaluated the adenotonsillar size using a flexible fiberoptic endoscope. Results: The percentage of patients with an OAHI of 1 increased from 3 to 22, 36, and 38 at t1, t4, and t6, respectively (2 12.2; P .05). We observed a decrease in the respiratory disturbance indexfrom1.4 (t0) to 0.8 (t3) (P.05)andthe centralapneaindexfrom1.2 (t0) to 0.1 (t4) (P.0001). We had to temporarily suspend treatment for 3 patients at t1, t4, and t5 because of severe obstructive sleep apnea. The percentage of patients with severe adenotonsillar hypertrophy was significantly higher at t4 and t5 than at t0. The OAHI directly correlated with the adenoid size (adjusted for age) (P .01) but not with the tonsil size and IGF-1 levels. Conclusion: Long-termGHtreatment in patients withPWSis safe; however,werecommend annual polysomnography and adenotonsillar evaluation
Prevalence of pathogenetic MC4R mutations in Italian children with early onset obesity, tall stature and familial history of obesity.
BackgroundMelanocortin-4-receptor (MC4R) mutations represent the most frequent genetic cause of non-syndromic early onset obesity. Children carrying MC4R mutations seem to show a particular phenotype characterized by early onset, severe obesity and high stature. To verify whether MC4R mutations are associated with this particular phenotype in the Italian pediatric population, we decided to screen the MC4R gene in a group of obese children selected on the basis of their phenotype.MethodsTo perform this study, a multicentric approach was designed. Particularly, to be enrolled in the study subjects needed to meet the following criteria: Body mass index ≥ 3 deviation scores according to age and sex, familiar history of obesity (at least one parent obese), obesity onset before the 10 years old, height ≥ 2 deviation scores. The coding region of MC4R gene was screened in 240 obese children (mean age 8.3 ± 3.1, mean BMI 30.8 ± 5.4) and in 200 controls (mean age 8.1 ± 2.8; mean BMI 14.2 ± 2.5).ResultsThree mutations have been found in five obese children. The S127L (C380T), found in three unrelated children, had been described and functionally characterized previously. The Q307X (C919T) and the Y332H (T994C) mutations were found in two patients. Functional studies showed that only Q307X impaired protein function.ConclusionThe low prevalence of MC4R mutations (1.6%) in this group of obese children selected according to the obesity degree, the tall stature and the family history of obesity was similar to the prevalence observed in previous screenings performed in obese adults and in not phenotypically selected obese children
A computational approach to identify whole genome homozygosity mapping across multiple SNP mapping experiments
The recent development of microarray platforms, capable to genotype more than thousands of single nucleotide polymorphisms (SNPs) in individuals, had provided an opportunity to rapidly identify susceptibility loci for complex phenotypes. High density SNP mapping arrays have been widely applied to association studies, to copy number (CN) analysis in cancers and recently to investigate the role of homozygosity extended regions in individuals. Long stretches of CN neutral and homozygous SNPs, defined as runs of homozygosity (ROHs) can be found either in a single individual or shared across samples. The identification of ROHs among affected individuals of the same family or among unrelated ones with same disease, can underline loci potentially implicated in the genetic basis of the disease under study. Therefore the identification of ROHs in affected individuals or pathological datasets gives a chance to identify disease associated loci and new causative mutations. In order to identify ROHs pattern across Affymetrix SNP mapping datasets, we developed a computational strategy including several computational steps: 1) loss of heterozygosity analysis by dChip2007 software; 2) a within-subject step allowing the identification of ROHs in a single sample; 3) an across-subject step extracting the ROH fingerprint of the dataset and 4) the identification of a common ROHs pattern based on frequency across the dataset under study, varying the number of individuals carrying common ROHs; 5) the annotation step allowing the association of genes to selected ROHs. In order to obtain an effective ROHs visualization, we use dChip software for the entire samples dataset. We assess our strategy to two SNP mapping datasets including 100K leukemia and 250K congenital recessive diseases. The procedure allowed the identification of a unique genetic ROH fingerprint of clinical datasets potentially important to discover new diseases associated loci suitable for further investigations
A Multicenter Retrospective Survey regarding Diabetic Ketoacidosis Management in Italian Children with Type 1 Diabetes
We conducted a retrospective survey in pediatric centers belonging to the Italian Society for Pediatric Diabetology and Endocrinology. The following data were collected for all new-onset diabetes patients aged 0-18 years: DKA (pH < 7.30), severe DKA (pH < 7.1), DKA in preschool children, DKA treatment according to ISPAD protocol, type of rehydrating solution used, bicarbonates use, and amount of insulin infused. Records (n = 2453) of children with newly diagnosed diabetes were collected from 68/77 centers (87%), 39 of which are tertiary referral centers, the majority of whom (n = 1536, 89.4%) were diagnosed in the tertiary referral centers. DKA was observed in 38.5% and severe DKA in 10.3%. Considering preschool children, DKA was observed in 72%, and severe DKA in 16.7%. Cerebral edema following DKA treatment was observed in 5 (0.5%). DKA treatment according to ISPAD guidelines was adopted in 68% of the centers. In the first 2 hours, rehydration was started with normal saline in all centers, but with different amount. Bicarbonate was quite never been used. Insulin was infused starting from third hour at the rate of 0.05-0.1 U/kg/h in 72% of centers. Despite prevention campaign, DKA is still observed in Italian children at onset, with significant variability in DKA treatment, underlying the need to share guidelines among centers
Endocrine features of Prader-Willi syndrome: a narrative review focusing on genotype-phenotype correlation
Prader-Willi syndrome (PWS) is a complex genetic disorder caused by three different types of molecular genetic abnormalities. The most common defect is a deletion on the paternal 15q11-q13 chromosome, which is seen in about 60% of individuals. The next most common abnormality is maternal disomy 15, found in around 35% of cases, and a defect in the imprinting center that controls the activity of certain genes on chromosome 15, seen in 1-3% of cases. Individuals with PWS typically experience issues with the hypothalamic-pituitary axis, leading to excessive hunger (hyperphagia), severe obesity, various endocrine disorders, and intellectual disability. Differences in physical and behavioral characteristics between patients with PWS due to deletion versus those with maternal disomy are discussed in literature. Patients with maternal disomy tend to have more frequent neurodevelopmental problems, such as autistic traits and behavioral issues, and generally have higher IQ levels compared to those with deletion of the critical PWS region. This has led us to review the pertinent literature to investigate the possibility of establishing connections between the genetic abnormalities and the endocrine disorders experienced by PWS patients, in order to develop more targeted diagnostic and treatment protocols. In this review, we will review the current state of clinical studies focusing on endocrine disorders in individuals with PWS patients, with a specific focus on the various genetic causes. We will look at topics such as neonatal anthropometry, thyroid issues, adrenal problems, hypogonadism, bone metabolism abnormalities, metabolic syndrome resulting from severe obesity caused by hyperphagia, deficiencies in the GH/IGF-1 axis, and the corresponding responses to treatment
Proposta di un manuale di accreditamento per i centri di assistenza e cura al bambino obeso
Studio di linkage in famiglie di pazienti affetti da Iperinsulinismo Congenito dell'Infanzia (CHI) mediante tecnologie di genotipizzazione ad alta risoluzione di SNP
L' Iperinsulinismo Congenito dell'Infanzia (CHI, MIM # 256450) \ue8 una patologia grave caratterizzata da una inappropriata
secrezione di insulina da parte delle beta-cellule pancreatiche, che causa severa ipoglicemia spesso pericolosa per la stessa vita del
paziente. La patologia si presenta eterogenea dal punto di vista clinico, genetico, morfologico e funzionale e comporta un'estrema
variabilit\ue0 nell'et\ue0 dell'esordio della malattia, nella severit\ue0 con cui si manifesta e nella risposta alle cure mediche; \ue8 una delle
principali cause di danni neurologici e diabete iatrogeno (Aynsley-Green 2000; Cosgrove 2004; Dunne 2005). Nei pazienti affetti da
CHI sono state evidenziate mutazioni in differenti geni, ed \ue8 stata dimostrata un' ereditariet\ue0 di tipo sia autosomico recessivo che
dominante (de Lonlay 2005; Henwood 2004). Circa il 50% casi sono causati da mutazioni sui geni ABCC8 (MIM # 600509) e
KCNJ11 (MIM # 600937) che codificano per entrambe le subunit\ue0 (KIR6.2 e SUR1) costituenti il canale del potassio ATP
dipendente nelle beta--cellule (KATP). Circa il 5% dei pazienti affetti da CHI ha mutazioni dominanti nel gene che codifica per la
glutammatodeidrogenasi (GDH) (Stanley 1998). Sono noti anche rari casi di CHI causata da mutazioni attivanti sul gene della
glucokinasi (GCK) (Glaser 1998). Recentemente sono state trovate mutazioni nel gene dell'idrossi-L-3-acildeidrogenasi a catena
corta (SCHAD) (Clayton 2001). E' stata anche descritta, in pochi pazienti, una sindrome singolare di ipoglicemia, conseguente
all'esercizio fisico, la cui eziologia genetica rimane sconosciuta (Meissner 2001). Dal punto di vista istopatologico sono state
distinte due diverse forme: si pu\uf2 avere un coinvolgimento diffuso delle beta-cellule nel pancreas (forma diffusa, Di-HI), o
un'iperplasia adenomatosa focale (forma focale, Fo-HI), dove regioni distinte del pancreas appaiono essere coinvolte, mentre le
aree circostanti sono istologicamente e funzionalmente normali. La forma diffusa della malattia \ue8 causata da mutazioni germinali e
interessa l'intero corpo del pancreas (Goossens 1989). La forma focale invece \ue8 causata dalla perdita di una porzione del
cromosoma materno (11p15) associata a mutazioni ereditate dall'allele paterno (Verkarre 1998).
In questo panorama comunque, per circa il 50% dei pazienti affetti, non \ue8 stata ancora determinata un'eziologia genica precisa,
suggerendo cos\uec l'ipotesi che altri geni ad oggi sconosciuti possano essere coinvolti. Sono stati proposti molti geni quali candidati
(Sund 2001; Molven 2002; Ashcroft 2005) ad esempio fattori di trascrizione che regolano lo sviluppo del pancreas, molti dei quali
regolano anche la trascrizione di geni codificanti ormoni, oppure enzimi o recettori che intervengono nell' omeostasi del glucosio
(Molven 2002).
Vista la lunga lista di geni candidati i Polimorfismi a Singolo Nucleotide (SNPs) costituiscono dei marcatori validi per evidenziare
nuovi loci genici nelle famiglie di pazienti con CHI, negativi per mutazioni, e quindi contribuire a comprendere il ruolo dei canali
KATP dipendenti sull'eziologia di patologie che coinvolgano la funzionalit\ue0 delle beta cellule (Ashcroft 2006). Gli SNPs rappresentano variazioni del genoma generate dalla mutazione di una singola base nel DNA e costituiscono la fonte pi\uf9 semplice e comune del polimorfismo genico nel genoma umano. Gli SNPs sono circa il 90% di tutti i polimorfismi del DNA e il singolo nucleotide alterato pu\uf2 essere compreso sia nelle regioni codificanti che in quelle non codificanti. La frequenza degli SNPs \ue8 di uno ogni 100-300 basi distribuite lungo i 3 miliardi di basiche costituiscono il genoma umano (The International HapMap Consortium 2005). Molti SNPs non influenzano la biologia o le funzioni fisiologiche dell'ospite, tuttavia i ricercatori ritengono che alcuni SNP favoriscano la predisposizione alla malattia o influenzino la risposta a farmaci ed altre terapie (Ventre 2001). L'avanzamento senza precedenti nella mappatura degli SNPs del genoma umano ha avuto un effetto notevole sul progresso della ricerca delle malattie genetiche. Le mappature degli SNPs stanno contribuendo ad identificare migliaia di marcatori lungo tutto il genoma facilitando l'analisi di mappe pi\uf9 grandi generate dai ricercatori nel Progetto Genoma che con la ditta "Celera Genetics" ha fornito, nel 2000, la descrizione completa del genoma umano (Ventre 2001; Goddard 2002). Da un punto di vista analitico, la possibilit\ue0 di identificare marcatori multipli implica la necessit\ue0 di applicare metodi statistici avanzati e strumenti bioinformatici applicati alla genetica molecolare per l'identificazione di correlazioni tra aplotipi e fenotipi in gruppi familiari. I test statistici multivariati, opportunamente corretti per limitare l'effetto delle comparazioni multiple sulle soglie di confidenza, possono essere applicati per individuare marcatori specifici e associazioni tra l' aplotipo di un locus e i geni che influenzano il fenotipo patologico (Di 2005; Liu 2003; Freimer 2005).
Dai dati della letteratura si evince che l'analisi di SNPs ha contribuito ad identificare i geni multipli connessi con malattie complesse (Meaburn 2006; Carlson 2004) quali la malattia di Alzheimer (Strittmatter 1996), il diabete di tipo 2 (Altshuler 2000), il diabete di tipo I (Florez 2003) ed altre malattie autoimmuni (Ueda 2003). Queste associazioni sono difficili da rivelare con i metodi convenzionali di "gene-hunting" perch\ue9 un singolo gene alterato pu\uf2 dare soltanto un piccolo contributo alla genesi della malattia. Parallelamente all'utilizzo degli SNPs per studi di associazione in malattie poligeniche si \ue8 pensato che questi marcatori potessero essere altrettanto validi se impiegati per l'analisi di linkage in malattie monogeniche (Matise 2000; Wilson 2000; Shepard 2000; Sellick 2004). Pochi studi fino ad ora hanno utilizzato l'analisi di SNPs per studi di linkage in patologie genetiche con trasmissione di tipo mendeliano, anche se molti studi supportano l'ipotesi che un set di SNPs ad alta densit\ue0 possa fornire un numero di informazioni equiparabile a quelle ottenute con screening genomici che utilizzano altri marcatori quali microsatelliti o
short-tandem-repeat polymorphisms (STRPs) (Wilson 2000; Matise 2003; Shepard 2004; Sellick 2004). Negli ultimi due anni tuttavia sono comparsi in letteratura studi che hanno utilizzato piattaforme ad alta densit\ue0 di SNPs per individuare nuovi geni coinvolti in malatie autosomiche, sia dominanti che recessive, quali diabete neonatale, craniosinostosi, displasia renale (Sellick 2004), leucodistrofia di Pelizaeus-Merzbacher (Uhlenberg 2004), Congenital vertical Talus e Charcot-Marie Tooth (Shrimpton 2004) e microcefalia primaria (Shen 2005). Il sequenziamento dei geni candidati evidenziati con l'analisi di linkage ha permesso di riscontrare nei casi descritti la presenza di mutazioni puntiformi.
In questo contesto di analisi genomiche si sono sviluppate negli ultimi anni numerose piattaforme (Affymetrix, Applied Biosystems, Illumina) per l'analisi simultanea di migliaia di SNPs, attraverso le quali \ue9 possibile identificare loci genici interessanti, associati a patologie a caratteri complessi (Butcher 2004). In particolare con i 2 Array che costituiscono il GeneChip Human Mapping 100K Set della ditta Affymetrix si possono analizzare contemporaneamente pi\uf9 di 100000 SNPs con un intervallo medio tra i vari marcatori di 23.6 Kb (Meaburn 2006; Matsuzaki 2004).
Sulla base di queste considerazioni intendiamo utilizzare la piattaforma Affymetrix per lo studio della variabilit\ue0 genetica e studio di linkage in famiglie di pazienti affetti da Iperinsulinismo Congenito dell'Infanzi
- …