PubMed Health⌕ Search

Biomedical subjects

Giorgio Tonini

Publications and source records attributed to Giorgio Tonini.

5 recordsLinked to original sources
PubMed2006

A SALL4 zinc finger missense mutation predicted to result in increased DNA binding affinity is associated with cranial midline defects and mild features of Okihiro syndrome.

Truncating mutations of the gene SALL4 on chromosome 20q13.13-13.2 cause Okihiro and acro-renal-ocular syndromes. Pathogenic missense mutations within the SALL4 or SALL1 genes have not yet been reported, raising the question which phenotypic features would be associated with them. Here we describe the first missense mutation within the SALL4 gene. The mutation results in an exchange of a highly conserved zinc-coordinating Histidine crucial for zinc finger (ZF) structure within a C2H2 double ZF domain to an Arginine. Molecular modeling predicts that this exchange does not result in a loss of zinc ion binding but leads to an increased DNA-binding affinity of the domain. The index patient shows mild features of Okihiro syndrome, but in addition cranial midline defects (pituitary hypoplasia and single central incisor). This finding illustrates that the phenotypic and functional effects of SALL4 missense mutations are difficult to predict, and that other SALL4 missense mutations might lead to phenotypes not overlapping with Okihiro syndrome.

Base Sequence↗
PubMed2005

KCNJ11 activating mutations in Italian patients with permanent neonatal diabetes.

Permanent neonatal diabetes mellitus (PNDM) is a rare condition characterized by severe hyperglycemia constantly requiring insulin treatment from its onset. Complete deficiency of glucokinase (GCK) can cause PNDM; however, the genetic etiology is unknown in most PNDM patients. Recently, heterozygous activating mutations of KCNJ11, encoding Kir6.2, the pore forming subunit of the ATP-dependent potassium (K(ATP)) channel of the pancreatic beta-cell, were found in patients with PNDM. Closure of the K(ATP) channel exerts a pivotal role in insulin secretion by modifying the resting membrane potential that leads to insulin exocytosis. We screened the KCNJ11 gene in 12 Italian patients with PNDM (onset within 3 months from birth) and in six patients with non-autoimmune, insulin-requiring diabetes diagnosed during the first year of life. Five different heterozygous mutations were identified: c.149G>C (p.R50P), c.175G>A (p.V59M), c.509A>G (p.K170R), c.510G>C (p.K170N), and c.601C>T (p.R201C) in eight patients with diabetes diagnosed between day 3 and 182. Mutations at Arg50 and Lys170 residues are novel. Four patients also presented with motor and/or developmental delay as previously reported. We conclude that KCNJ11 mutations are a common cause of PNDM either in isolation or associated with developmental delay. Permanent diabetes of non autoimmune origin can present up to 6 months from birth in individuals with KCNJ11 and EIF2AK3 mutations. Therefore, we suggest that the acronym PNDM be replaced with the more comprehensive permanent diabetes mellitus of infancy (PDMI), linking it to the gene product (e.g., GCK-PDMI, KCNJ11-PDMI) to avoid confusion between patients with early-onset, autoimmune type 1 diabetes.

DNA Mutational Analysis↗
PubMed2004

Refractive evaluation in children with growth defect.

PURPOSE: Growth hormone (GH) is considered essential for postnatal somatic growth, exerting its effects on growth by hepatic production of IGF-I. IGF and other growth factors interact with the developing ocular tissues by influencing the synthesis of the extracellular matrix of the sclera and by inducing angiogenesis. The association between optic nerve hypoplasia, reduced retinal vascularization and GH deficiency (GHD) is well known. The purpose of this study is to evaluate the possible influence of congenital GHD on the refraction and on the emmetropization process. METHODS: Eighty children with congenital GHD had a thorough ophthalmologic examination, including cycloplegic refraction and axial length measurement. As a control group we enrolled 483 healthy children. RESULTS: In accordance with other epidemiological studies, the control group showed a slightly myopic mean defect; on the contrary, in GHD group we found a hyperopic defect, related to a shorter axial length, with statistically significant differences. CONCLUSIONS: Our findings emphasise the possible role of growth hormone in ocular development, and its interaction with the physiological process of emmetropization.

Adolescent↗
PubMedDate not supplied

Maturity-onset diabetes of the young with necrobiosis lipoidica and granuloma annulare.

We describe a 12-year-old white girl with granuloma annulare localized to both ankles since she was five, necrobiosis lipoidica in the left pretibial region since she was ten, and a recent history of weakness, migraine, and weight loss. After initial evaluation, high fasting blood glucose levels and high hemoglobin A1c were found. The family history for non-insulin-dependent diabetes was suggestive of maturity-onset diabetes of the young. Coexistence of necrobiosis lipoidica and granuloma annulare, together with a family history of non-insulin-dependent diabetes, the age of onset, and the absence of ketosis, are specific features making possible, a clinical diagnosis. Genetic confirmation may not be so easily accessible or necessary.

Child↗