Manuela Caruso-Nicoletti

Whole Genome SNP Genotyping and Exome Sequencing Reveal Novel Genetic Variants and Putative Causative Genes in Congenital Hyperinsulinism

Congenital hyperinsulinism of infancy (CHI) is a rare disorder characterized by severe hypoglycemia due to inappropriate insulin secretion. The genetic causes of CHI have been found in genes regulating insulin secretion from pancreatic β-cells; recessive inactivating mutations in the ABCC8 and KCNJ11 genes represent the most common events. Despite the advances in understanding the molecular pathogenesis of CHI, specific genetic determinants in about 50 % of the CHI patients remain unknown, suggesting additional locus heterogeneity. In order to search for novel loci contributing to the pathogenesis of CHI, we combined a family-based association study, using the transmission disequilibrium test on 17 CHI patients lacking mutations in ABCC8/KCNJ11, with a whole-exome sequencing analysis performed on 10 probands. This strategy allowed the identification of the potential causative mutations in genes implicated in the regulation of insulin secretion such as transmembrane proteins (CACNA1A, KCNH6, KCNJ10, NOTCH2, RYR3, SCN8A, TRPV3, TRPC5), cytosolic (ACACB, CAMK2D, CDKAL1, GNAS, NOS2, PDE4C, PIK3R3) and mitochondrial enzymes (PC, SLC24A6), and in four genes (CSMD1, SLC37A3, SULF1, TLL1) suggested by TDT family-based association study. Moreover, the exome-sequencing approach resulted to be an efficient diagnostic tool for CHI, allowing the identification of mutations in three causative CHI genes (ABCC8, GLUD1, and HNF1A) in four out of 10 patients. Overall, the present study should be considered as a starting point to design further investigations: our results might indeed contribute to meta-analysis studies, aimed at the identification/confirmation of novel causative or modifier genes.

Growth and growth hormone in children during and after therapy for acute lymphoblastic leukaemia

Growth impairment and growth hormone (GH) deficiency have been reported in children treated for acute lymphoblastic leukaemia (ALL). We have studied growth and GH secretion in a group of 50 patients, affected by ALL, during a 2- to 5-year period after diagnosis, and in 12 “long-term-survivors”. We observed a significant decrease in growth velocity during the 1st year (in particular during the first 6 months) of therapy and a catch-up growth after the end of therapy. “Longterm survivors” did not exhibit a significant reduction of height standard deviation score (SDS), as compared to height SDS at diagnosis. None of the patients showed GH deficiency. Our data indicate that chemotherapy significantly affects growth of patients treated for ALL, whereas radiotherapy-at the doses used in this study-does not induce GH deficiency, at least not within 9 years after diagnosis.

Elevated incidence of hypospadias in two sicilian towns where exposure to industrial and agricultural pollutants is high

We found significant elevated incidence of hypospadias in two towns in Southeastern Sicily selected on the basis of the presence of intense industrial (Augusta) and agricultural (Vittoria) activities. Cases and controls were chosen in records collected from a surveillance system on abnormal live births in the same area and in a large city (Catania) located in an area at low risk of exposure to environmental pollutants. From 1991 to 1998, 16 cases of isolated hypospadias were recorded among male live births in Augusta (12.1 per 1000 male live births) and 24 cases in Vittoria (7.4 per 1000 male live births) with an incidence significantly higher than that expected (3.2 per 1000 in Southeastern Sicily). Relative risks in Augusta and Vittoria were 3.8 (95% confidence interval: 2.16-6.14) and 2.3 (95% confidence interval: 1.48-3.43; P=0.00003 and 0.04, respectively). In Augusta, the incidence of hypospadias was higher than in Vittoria. Significant log odds ratios were found for occupational exposure in fathers both in Augusta and Vittoria (P=0.0478 and 0.026, respectively). However, daily contact with pollutants in Augusta may not be sufficient by itself to determine hypospadias and other factors might be involved. Similar factors may act also in Vittoria. Thus, contact with large amounts of pesticides is, by itself, a risk factor for hypospadias, though genetic and other environmental factors might be involved.

Hyporesponsiveness to intradermal administration of hepatitis B vaccine in insulin dependent diabetes mellitus

The immune response to intradermal or intramuscular hepatitis B vaccine in 18 children with insulin dependent diabetes mellitus (IDDM) compared with 24 healthy children was studied. Patients were divided into responders, hyporesponders, and non-responders according to their antihepatitis B serum concentrations after hepatitis B vaccination. We also studied HLA class II antigen distribution and did delayed type hypersensitivity (DTH) tests on children with IDDM and controls.  No difference in the immune response (antihepatitis B surface antigen antibody titres) was found with intramuscular administration, whereas with intradermal administration a statistically lower immune response (p < 0.001) was observed in children with IDDM vcontrols. This hyporesponsiveness cannot be attributed to HLA class II antigen distribution because their frequency was the same in both groups of children with IDDM.  It is suggested that the poor immune response to intradermal hepatitis B vaccine may be due to impaired macrophage activity resulting in failure of antigen presentation, which may be of importance in the immune dysfunction in children with IDDM. This hypothesis is suggested by a significantly lower score on a DTH test to a battery of antigens in the IDDM group when compared with controls. It is therefore suggested that when the hepatitis B vaccination is offered to children with IDDM it may be preferable to give it intramuscularly.

GH secretion in a cohort of children with pseudohypoparathyroidism type Ia.

Pseudohypoparathyroidism type Ia (PHP-Ia) is characterized by Albright’s hereditary osteodistrophy (AHO) and resistance to hormones that act via the α subunit of the Gs protein (Gsα) protein, ie PTH, TSH, FSH/LH, and, as recently described in limited series, GHRH. However, the current lack of data on GHRH secretion, obesity and short stature included in the AHO phenotype hampers interpretation of GH secretory status and its effects on these subjects. We evaluated GH secretion after GHRH plus arginine (Arg) stimulus, IGF-I levels and anthropometric features in an exclusively pediatric population of 10 PHP-Ia subjects. Of our PHP-Ia children, 5 out of 10 (50%) showed impaired GH responsiveness to the provocative test, with a lower prevalence than the 75–100% previously reported. A negative correlation (p=0.024) was found between GH secretion and body mass index (BMI), whereas no correlation emerged between GH and IGF-I values (p=0.948). Height and growth velocity did not significantly differ between GH-deficient and GH-sufficient subjects. In the 5 GH-deficient patients, GHRH resistance could arguably be responsible for hormonal impairment; however, 3 of them were obese, showing normal stature and IGF-I levels: the increased BMI in these subjects could influence GH secretion and its effects. In conclusion, GH deficiency is frequent among PHP-Ia children and its prevalence is variable, two factors indicating that GH secretory testing should be part of the routine management of this patient group. It could be argued that GHRH resistance is the pathogenetic mechanism in most patients, but further studies on GHRH secretion are needed to define which values can be considered as raised. Lastly, because BMI has been indicated as a major determinant of evoked adult GH response to provocative testing, GH levels related to increased BMI also in childhood could be helpful in defining GH assessment in obese or overweight PHP-Ia children.

Growth hormone secretion in adult patients with thalassaemia

Background and Objectives  Growth retardation and short stature are frequent clinical features of patients with beta‐thalassaemia major. Dysfunction of the GH–IGF‐1 axis has been described in many thalassaemic children and adolescents with short stature and reduced growth velocity. Several studies have demonstrated that recombinant GH treatment improves growth velocity in these patients, although response to the treatment is variable and not predictable. A reassessment of the GH–IGF‐1 axis must be performed in young adults with childhood‐onset GH deficiency (GHD), after attainment of final height, to select those who are candidates for replacement therapy as adults. To our knowledge there are no data available on retesting the GH–IGF‐1 axis in adult thalassaemic patients with childhood‐onset GHD. The aim of our study was to investigate GH secretion in adult thalassaemic patients with childhood‐onset GHD.

Assessment of serum IGF-I concentrations in the diagnosis of isolated childhood-onset GH deficiency: A proposal of the Italian Society for Pediatric Endocrinology and Diabetes (SIEDP/ISPED)

The diagnosis of GH deficiency (GHD) is based on the measurement of peak GH responses to pharmacological stimuli. Pharmacological stimuli, however, lack precision, accuracy, are not reproducible, are invasive, non-physiological and some may even be hazardous. Furthermore, different GH commercial assays used to measure GH in serum yield results that may differ considerably. In contrast to GH, IGF-I can be measured on a single, randomly-obtained blood sample. A review of the available data indicates that IGF-I measurement in the diagnosis of childhood-onset isolated GHD has a specificity of up to 100%, with a sensitivity ranging from about 70 to 90%. We suggest an algorithm in which circulating levels of IGF-I together with the evaluation of auxological data, such as growth rate and growth, may be used to assess the likelihood of GHD in pre-pubertal children.

Genetic Analysis of Italian Patients with Congenital Hyperinsulinism of Infancy

Background/Aims: Congenital hyperinsulinism of infancy is a rare disease that needs prompt treatment to avoid brain damage. There are currently no data regarding the clinical and molecular features of Italian patients. Methods: Thirty-three patients with HI and their parents were included. Consanguinity was reported in six patients. Half of patients were macrosomic at birth. None had raised 3-hydroxybutyrylcarnitine or hyperammonemia. Molecular analysis of ABCC8 and KCNJ11 genes was performed in all patients, and subjects with no mutation underwent analysis of HNF4A and GCK. GLUD1 and HADH genes were analyzed in a patient with leucine sensitivity. Results: Mutations in the ABCC8 and KCNJ11 genes were found in 45% of the patients (6 novel). No mutations in HNF4A, GLUD1 and GCK genes were found. Recessive mode of inheritance was found in 21% of patients. A single heterozygous mutation was identified in 24% of probands. 72% of the patients were responsive to medical treatment, and 44% of the 17 patients with no identified mutation achieved spontaneous remission. Nine children, unresponsive to medical therapy, underwent pancreatectomy. Conclusion: This is the first report on hyperinsulinism of infancy in Italy, confirming the complexity of the clinical forms and the heterogeneity of the genetic causes of the disease.

No Difference in Pubertal Growth and Final Height between Treated Hypogonadal and Non-Hypogonadal Thalassemic Patients

Background: Many factors can negatively affect growth in thalassemic patients, and hypogonadism has been considered as the main factor responsible for their pubertal growth failure. Objective: To evaluate the influence of hypogonadism and its treatment on pubertal growth and final height in thalassemic patients. Methods: We compared the growth of 28 hypogonadal thalassemic patients in whom puberty was induced to that of 25 patients in whom puberty occurred spontaneously. Results: In both groups of patients we observed reduced peak height velocity (induced puberty: females 4.9 ± 2.1, males 6.0 ± 1.8 cm/year; spontaneous puberty: females 6.1 ± 1.5, males 7.3 ± 2.1 cm/year) and pubertal height gain (induced puberty: females 11.3 ± 4.0, males 18.0 ± 4.5 cm/year; spontaneous puberty: females 15.8 ± 2.7, males 18.1 ± 5.3 cm/year) and a short final height (induced puberty: females –1.8 ± 0.7, males –2.1 ± 1.0 SDS; spontaneous puberty: females –2.3 ± 1.0, males –1.9 ± 1.0 SDS). Conclusions: Poor pubertal growth is present in thalassemic patients regardless of hypogonadism. Other factors are responsible for the reduced growth spurt and the final short stature observed in these patients.

Growth and development in white patients with sickle cell diseases.

We have evaluated height, weight, bone age, somatome-din-C levels, and pubertal development in 114 Sicilian patients affected by sickle cell diseases (SCDs). Thirty-one had homozygous sickle hemoglobin (SS), 55 S-β0 thalassemia, and 28 S-β+ thalassemia. In both children and adults, the mean height and weight were 1 SD below the normal mean for age. The height was below the normal range only in a few subjects (8 children and 4 adult women). Somatomedin-C levels were within the normal range in most of the patients (37/44 children and 17/22 adults). Bone age revealed a slight delay in skeletal maturation (mean chronological age and bone age were 7.7 ± 3 and 7.11 ± 2.9 respectively; p < 0.05). Mean age at menarche was increased compared to normal subjects. Our findings show that Sicilian patients with SCD exhibit a moderate delay of growth and adolescence but attain a final height within the normal range.