Identification of ring Y chromosome: cytogenetic analysis, Southern blot and fluorescent in situ hybridization.

A young male with a 45, X/46, X, r(Y)/47, X, r(Y), r(Y)/48, X, r(Y), r(Y), r(Y) karyotype was described. The phenotype was substantially characterized by short stature (< 3rd centile) and by a scrotal hypospadias with a normal sized penis. Fluorescent in situ hybridization (FISH) and molecular analysis by X and Y chromosomes specific probes were performed to identify the origin of the marker chromosomes which had been impossible to define by conventional and high resolution cytogenetics techniques. Small rings was identified as Y-derived ring chromosomes, lacking the entire heterochromatic portion of the long arm and the very distal tip of the short arm. The correlation between the phenotype and the chromosome constitution of the propositus was discussed.

[Study of the beta cell function in type I diabetes by the determination of peptide C after glucagon challenge]. / Studio della funzionalità beta-cellulare nel diabete tipo I mediante dosaggio del peptide C dopo carico con glucagone.

In 35 patients (13F/22M; age range 2-15 years), affected by insulin dependent diabetes mellitus (IDDM), basal and glucagon stimulated C peptide was determined and correlated with the daily insulin requirement (U/Kg/die), the glycosylated hemoglobin (HbA1c), the age of onset (months) and the length of the illness (months). The results of C peptide determinations are illustrated in tab. 1: in 20 patients (group I) the basal value of C peptide is higher than 1 ng/ml and increases after glucagon load; in 15 patients (group II) the basal value of C peptide is lower than 1 ng/ml; in 9 ones (group IIA) of these 15 a glucagon load does not elicit a residual insulin secretion; in the other 6 ones (group IIB) a significative C peptide increase is observed after glucagon load. A better metabolic control (p less than 0.01); Student t test) and a shorter length of the illness (p less than 0.05; Mann-Withney U test) was noticed in the group I in comparison with the group IIA, in which no insulin reserve, even after glucagon load, was demonstrated (tab. 2). However, no difference in the metabolic control, insulin requirement, age of onset or length of the illness resulted between group IIA and group IIB (in which an insulin reserve had been demonstrated only after glucagon load). The basal C peptide evaluation and follow up is useful in the assessment of the individual case of IDDM: a glucagon load may demonstrate a residual insulin reserve in some patients with a low basal C peptide.

[Significance of the evaluation of C-peptide in children with type 1 diabetes mellitus]. / Interesse della valutazione del peptide C nel bambino affetto da diabete mellito tipo 1.

In type I diabetes mellitus (DM) the presence of C peptide (Cp), whose determination is unaffected by exogenous insulin, is considered expression of a residual beta-cell activity, which allows a better metabolic control. In 35 children affected by type I DM the fasting Cp was measured: in 18 cases (1st group) a value greater than or equal to 1 ng/ml was observed, while in the remaining 17 (2nd group) the Cp value was less than 1 ng/ml. A statistical comparison between the two groups demonstrated that in the first one a better metabolic control was achieved with a daily lower insulin dosage. Moreover in the 1st group the onset of the disease was more recent, while there was no difference between the two groups with regard to the age at diagnosis. The Cp evaluation and follow-up is useful in the assessment of the individual case; furthermore, on the basis of these studies, an immunosuppressive treatment may be considered during the early phase of the disease, when a residual beta-cell activity is demonstrated.