A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

Pseudopapilledema and congenital disc anomalies in growth hormone deficiency

Optic nerve hypoplasia is a congenital disc anomaly associated with growth hormone deficiency (GHD). Pseudotumor cerebri is an adverse event associated with growth hormone treatment (hGH) and manifested by increased intracranial pressure and papilledema. Pseudopapilledema is a generic ophthalmologic term encompassing several conditions, including congenital disc anomalies. It is benign and can be distinguished from papilledema by physical examination. The objective of this report is to document that congenital disc abnormalities, which can be confused with papilledema, occur in children with GHD. Three patients with GHD had fundoscopic examinations suggestive of papilledema and possibly pseudotumor cerebri. The abnormal optic nerves were characteristic of pseudo-papilledema, and appear to be a variant of optic nerve hypoplasia. The finding of optic disc abnormality during hGH may reflect pseudo-papilledema and not pseudotumor cerebri. Of equal importance, the reported patients indicate that the finding of pseudopapilledema in short children should suggest the possibility of GHD.

Endocrine outcome in long-term survivors of low-grade hypothalamic/chiasmatic glioma

OBJECTIVE

We have evaluated the frequency of endocrine abnormalities in a large group of patients with hypothalamic/chiasmatic glioma (H/CG) and its correlation with the different forms of therapy.

DESIGN

Descriptive retrospective study using case note review analysis.

PATIENTS

The records of 68 children who survived H/CG were analysed. One third had neurofibromatosis. The mean age at tumour presentation was 5 years. The median time of follow-up was 3.6 years. Thirty-eight children received cranial radiation, of whom 17 also had surgery. Surgery was performed in a total of 24 patients. Fifteen patients received only chemotherapy. Eight children, all with neurofibromatosis, received no specific tumour treatment.

MEASUREMENTS

Endocrine dysfunction was determined by clinical manifestations and biochemical evaluation of hypothalamic-pituitary function.

RESULTS

Endocrine dysfunction occurred in 42% of the children. The most common disorder was GH deficiency (GHD). Of 50 children evaluated, 15 of the 19 with GHD received cranial irradiation (P < 0.05). HOwever, 15 children treated with more than 15 Gy grew normally. Precocious puberty was diagnosed in 11 patients. Nine patients, all treated with cranial irradiation, developed hypogonadotrophic hypogonadism. Of the 14 patients with hypothyroidism, 10 had surgery (P < 0.005). Hypoadrenalism and diabetes insipidus each occurred in eight patients, and were associated with multiple endocrine deficiencies and surgery. Endocrine deficiencies occurred in children with neurofibromatosis as frequently as children without neurofibromatosis but only when comparing those treated with cranial irradiation or surgery.

CONCLUSIONS

Nearly all studies assessing the patients with different tumour therapy evaluate patients wit different tumour types. This study investigates a specific and large population of patients with H/CG and correlates the different form of treatment with the endocrine outcome. Precocious puberty, in children with this tumour, is probably due to tumour location rather than oncological therapy. Conversely, although endocrine deficiencies can be a result of tumour location, the major causes of endocrine abnormalities were field irradiation and tumour surgery. A notable finding not previously reported is that endocrine dysfunction occurs less often in neurofibromatosis patients treated conservatively. Furthermore, this study documents that a significant number of young children grew normally despite receiving brain irradiation of greater than 45 Gy.

Arm span as measurement of response to growth hormone (GH) treatment in a group of children with meningomyelocele and GH deficiency

Children with meningomyelocele (MMC) frequently have impaired linear growth. A number have associated structural brain defects with resultant GH deficiency (GHD). Reproducible measurements of height or length in MMC patients are often hampered by lower limb contractures, spasticity, and scoliosis. Arm span has been proposed as a more reproducible measure of linear growth. Five MMC children documented to have GHD were treated with recombinant human GH (hGH) for 1-3 yr. Their height, arm span, and growth velocity were compared with 32 children with idiopathic GHD treated similarly with hGH. These measures are compared with normal children by being expressed as standard deviation scores. The results of this study indicate that arm span measurements in GHD MMC patients are almost identical to height measurements in idiopathic GHD patients both before and during hGH therapy. The physical condition of children with MMC makes reproducible longitudinal height measurements difficult. Routine determinations of arm span measurements for children with MMC will assist in recognizing growth failure as well as monitoring treatment results.