Clinical and Molecular Characteristics and Long-term Follow-up of Children With Pseudohypoparathyroidism Type IA.

CONTEXT: Pseudohypoparathyroidism type IA (PHPIA) is a rare genetic disorder characterized by hormone resistance and a typical phenotype named Albright hereditary osteodystrophy. Unawareness of this rare disease leads to delays in diagnosis. OBJECTIVE: The aims of this study were to describe the clinical and molecular characteristics of patients with genetically confirmed GNAS mutations and to evaluate their long-term outcomes. METHODS: A retrospective search for all patients diagnosed with PHPIA in 2 referral centers in Israel was conducted. RESULTS: Nine children (8 females) belonging to 6 families were included in the study. Five patients had GNAS missense mutations, 2 had deletions, and 2 had frameshift mutations. Four mutations were novel. Patients were referred at a mean age of 2.4 years due to congenital hypothyroidism (5 patients), short stature (2 patients), or obesity (2 patients), with a follow-up duration of up to 20 years. Early obesity was observed in the majority of patients. Elevated parathyroid hormone was documented at a mean age of 3 years; however, hypocalcemia became evident at a mean age of 5.9 years, about 3 years later. All subjects were diagnosed with mild to moderate mental retardation. Female adult height was very short (mean -2.5 SD) and 5 females had primary or secondary amenorrhea. CONCLUSION: Long-term follow-up of newborns with a combination of congenital hypothyroidism, early-onset obesity, and minor dysmorphic features associated with PHPIA is warranted and molecular analysis is recommended since the complete clinical phenotype may develop a long time after initial presentation.

Youth-onset type 2 diabetes in Israel: A national cohort.

BACKGROUND: Prevalence of youth-onset type 2 diabetes (T2D) has increased worldwide, paralleling the rise in pediatric obesity. Occurrence and clinical manifestations vary regionally and demographically. OBJECTIVES: We assessed the incidence, and clinical and demographic manifestations of youth-onset T2D in Israel. METHODS: In a national observational study, demographic, clinical, and laboratory data were collected from the medical records of children and adolescents, aged 10-18 years, diagnosed with T2D between the years 2008 and 2019. RESULTS: The incidence of youth-onset T2D in Israel increased significantly from 0.63/100,000 in 2008 to 3.41/100,000 in 2019. The study cohort comprised 379 individuals (228 girls [59.7%], 221 Jews [58.3%], mean age 14.7 ± 1.9 years); 73.1% had a positive family history of T2D. Mean body mass index (BMI) z-score was 1.96 ± 0.7, higher in Jews than Arabs. High systolic (≥ 130 mmHg) and diastolic blood pressure (≥ 85 mmHg) were observed in 33.7% and 7.8% of patients, respectively; mean glycosylated hemoglobin (A1c) level at diagnosis was 8.8 ± 2.5%. Dyslipidemia, with high triglyceride (>150 mg/dl) and low HDL-c (<40 mg/dl) levels, was found in 45.6% and 56.5%, respectively. Microalbuminuria and retinopathy were documented at diagnosis, 15.2% and 1.9%, respectively) and increased (36.7% and 4.6%, respectively) at follow-up of 2.9 ± 2.1 years. Criteria of metabolic syndrome were met by 224 (62.2%) patients, and fatty liver documented in 65%, mainly Jews. Psychosocial comorbidity was found in 31%. Treatment with metformin (45.6%), insulin (20.6%), and lifestyle modification (18%) improved glycemic control. CONCLUSION: Youth-onset T2D in Israel has increased significantly and presents a unique profile.

Long-Term Outcome of Patients with TPO Mutations.

INTRODUCTION: Thyroid peroxidase (TPO) deficiency is the most common enzymatic defect causing congenital hypothyroidism (CH). We aimed to characterize the long-term outcome of patients with TPO deficiency. METHODS: Clinical and genetic data were collected retrospectively. RESULTS: Thirty-three patients with primary CH caused by TPO deficiency were enrolled. The follow-up period was up to 43 years. Over time, 20 patients (61%) developed MNG. Eight patients (24%) underwent thyroidectomy: one of them had minimal invasive follicular thyroid carcinoma. No association was found between elevated lifetime TSH levels and the development of goiter over the years. CONCLUSIONS: This cohort represents the largest long-term follow up of patients with TPO deficiency. Our results indicate that elevated TSH alone cannot explain the high rate of goiter occurrence in patients with TPO deficiency, suggesting additional factors in goiter development. The high rate of MNG development and the risk for thyroid carcinoma indicate a need for long-term follow up with annual ultrasound scans.

The evolving role of whole-exome sequencing in the management of disorders of sex development.

OBJECTIVE: Disorders of sex development (DSD) are defined as congenital conditions in which the development of chromosomal, gonadal and anatomical sex is atypical. Despite wide laboratory and imaging investigations, the etiology of DSD is unknown in over 50% of patients. METHODS: We evaluated the etiology of DSD by whole-exome sequencing (WES) at a mean age of 10 years in nine patients for whom extensive evaluation, including hormonal, imaging and candidate gene approaches, had not identified an etiology. RESULTS: The eight 46,XY patients presented with micropenis, cryptorchidism and hypospadias at birth and the 46,XX patient presented with labia majora fusion. In seven patients (78%), pathogenic variants were identified for RXFP2, HSD17B3, WT1, BMP4, POR, CHD7 and SIN3A. In two atients, no causative variants were found. Mutations in three genes were reported previously with different phenotypes: an 11-year-old boy with a novel de novo variant in BMP4; such variants are mainly associated with microphthalmia and in few cases with external genitalia anomalies in males, supporting the role of BMP4 in the development of male external genitalia; a 12-year-old boy with a known pathogenic variant in RXFP2, encoding insulin-like 3 hormone receptor, and previously reported in adult men with cryptorchidism; an 8-year-old boy with syndromic DSD had a de novo deletion in SIN3A. CONCLUSIONS: Our findings of molecular etiologies for DSD in 78% of our patients indicate a major role for WES in early DSD diagnosis and management - and highlights the importance of rapid molecular diagnosis in early infancy for sex of rearing decisions.

Long-Term Follow-Up and Outcomes of Autoimmune Thyroiditis in Childhood.

Background: Autoimmune thyroiditis (AIT) is the most common cause of acquired hypothyroidism in children. The natural outcome of AIT in childhood has been reported previously however follow-up duration is generally short and results variable. Objectives: To characterize clinical and biochemical findings at presentation of AIT, evaluate long-term outcomes and assess which factors at presentation predict evolution over time. Study cohort: 201 children under 18 years of age at presentation (82% female) were enrolled. Subjects were divided into five subgroups according to thyroid stimulating hormone (TSH) level at referral. Results: Mean follow-up was 8.1 years (range 0-29 years). At presentation, 34% of patients had overt hypothyroidism, 32% subclinical hypothyroidism (SCH), 16% compensated hypothyroidism, 14% were euthyroid, and 3.7% had Hashitoxicosis. Children with overt hypothyroidism were younger (10.6 vs. 13.2 years) and had higher thyroid peroxidase antibody titers. At the time of the study, levothyroxine (LT4) therapy was required in 26% of children who were euthyroid at presentation, 56% of SCH patients, 83-84% of those with TSH above 10 mIU/L, and 57% of those with Hashitoxicosis. Over the years, 16% of children presenting with overt hypothyroidism stopped therapy. Free T4 at presentation was the only predictor of outcome over time. Conclusions: Our findings suggest that only 26% children who were euthyroid at presentation developed hypothyroidism, whereas over 50% of those with SCH went on to require treatment. Of those presenting with overt hypothyroidism, 16% recovered with time. The only predictive parameter for LT4 therapy at the end of the study was free T4 levels at presentation. Long-term follow-up is required to determine ongoing therapy needs and screen for additional autoimmune diseases.

A Novel Mutation (S54C) of the PAX8 Gene in a Family with Congenital Hypothyroidism and a High Proportion of Affected Individuals.

BACKGROUND: Congenital hypothyroidism (CH) is a common endocrine disorder in newborns. The cause of CH is thyroid dysgenesis in 80-85% of patients. Paired box gene 8 (PAX8) is a thyroid transcription factor that plays an important role in thyroid organogenesis and development. To date, 22 different PAX8 gene mutations have been reported. METHODS: Four generations of a Hungarian Jewish family were affected, and in the 3 generations studied, 9 males and 4 females were affected and 3 first-degree relatives were unaffected. Six were diagnosed at birth [thyroid-stimulating hormone (TSH) level 59-442 mU/l] and 7 at 2-48 years of age (TSH level 6-223 mU/l). One affected patient had thyroid hemiagenesis on ultrasound. RESULTS: Direct sequencing of the PAX8 gene revealed a novel single nucleotide substitution (c.162 A>T) in exon 2 that resulted in the substitution of the normal serine 54 with a cysteine (S54C), which segregated with elevated serum TSH levels. Other mutations of the same amino acid (S54G and S54R) have also been shown to produce functional impairment. CONCLUSION: We report a large family with a novel mutation in the PAX8 gene presenting with variable phenotype and with a high proportion of affected family members.

Long-term outcome of loss-of-function mutations in thyrotropin receptor gene.

BACKGROUND: Loss-of-function mutations in the thyrotropin receptor (TSHR) gene lead to resistance to TSH (RTSH) presenting with either congenital hypothyroidism (CH) or subclinical hypothyroidism (SCH). Despite several reports of patients with TSHR mutations, data on the long-term outcome of this condition are limited, and no consensus exists on the need for hormone replacement therapy. The aim of the present study was to assess the long-term outcome in children and adolescents with RTSH due to TSHR mutations. METHODS: The TSHR gene was sequenced in 94 subjects (aged 3 days-21 years) with either nonautoimmune SCH or CH with RTSH. RESULTS: Twenty-seven subjects (29%) carried mutations in TSHR. Fifteen infants were identified by neonatal screening, and the other 79 patients were detected in the process of testing for various other conditions or because of family occurrence of thyroid test abnormalities. Six different mutations were identified: c.484C>G (p.P162A), c.202C>T (p.P68S), c.790C>T (p.P264S), c.269A>C (p.Q90P), c.1957C>G (p.L653V), and c.1347C>T (p.R450C). Twelve subjects were homozygous, three were compound heterozygous, and 12 were heterozygous. Mean serum TSH levels at diagnosis and at last visit were significantly higher in patients with TSHR mutations than in those without mutations (29.04 vs. 14.15, p=0.002; 31.73 vs. 6.19, p<0.0001, respectively). Homozygous patients had a more severe phenotype (TSH 53.6 vs. 9.24, p<0.0001). Mean serum free thyroxine (fT4) levels at the last visit were significantly lower than at the first visit in the homozygous individuals (p=0.05) for a follow-up period of as long as 11 years. Heterozygous subjects had only mild hyperthyrotropinemia with stable TSH levels. However, homozygous subjects showed a trend toward increased TSH and decreased fT4 with time. CONCLUSION: SCH in heterozygotes with TSHR mutations is a stable compensated condition with an appropriately adjusted set point for pituitary-thyroid feedback that does not require replacement therapy. However, homozygous subjects, with incompletely compensated SCH, show reduced fT4 levels over time and may require levothyroxine treatment. Replacement therapy should be considered on an individual basis, and long-term follow up is recommended.

Novel microdeletions affecting the GNAS locus in pseudohypoparathyroidism: characterization of the underlying mechanisms.

CONTEXT: Pseudohypoparathyroidism type Ia (PHP1A) is a rare endocrine disorder characterized by hypocalcemia, hyperphosphatemia, multiple hormonal resistance, and features of Albright hereditary osteodystrophy. When the phenotype is present but not associated with hormonal resistance, it is called psedopseudohypoparathyroidism (PPHP). Both entities have been associated to GNAS haploinsufficiency, and are mostly caused by inherited inactivating mutations at GNAS gene that codes for the stimulatory alpha subunit of G protein, although the cause remains unidentified in approximately 30% of patients. OBJECTIVES: The aims of our work were 1) to identify GNAS locus defects in 112 patients with clinical diagnosis of PHP1A/PPHP and no point mutations at GNAS, to improve molecular diagnostic and genetic counseling; 2) to outline the underlying molecular mechanism(s). METHODS: Methylation-specific-multiplex ligation-dependent probe amplification, qPCR, array comparative genomic hybridization, and long-PCR were used to search for genomic rearrangements at chromosome 20q and to identify their boundaries. We used different bioinformatic approaches to assess the involvement of the genomic architecture in the origin of the deletions. RESULTS: We discovered seven novel genomic deletions, ranging from 106-bp to 2.6-Mb. The characterization of five of seven deletion breakpoints and the definition of the putative molecular mechanisms responsible for these rearrangements revealed that Alu sequences play a major role in determining the genetic instability of the region. CONCLUSION: We observed that deletions at GNAS locus represent a significant cause of PPHP/PHP1A and that such defects are mostly associated with Alu-mediated recombination events. Their investigation revealed to be fundamental as, in some cases, they could be misdiagnosed as imprinting defects.

Ghrelin and growth hormone secretagogue receptor (GHSR) genes are not commonly involved in growth or weight abnormalities in an Israeli pediatric population.

CONTEXT AND OBJECTIVE: Ghrelin and its receptor, growth hormone secretagogue receptor (GHSR), have key roles in appetite control and growth regulation. To date, only few mutations of GHSR have been identified in children with obesity and short stature. We hypothesized that mutations in ghrelin or GHSR will result in disrupted growth and weight regulation in children. DESIGN: A total of 98 subjects (38 females and 60 males) were enrolled with failure to thrive (FIT) (n=9), GH deficiency (GHD) (n=44), idiopathic short stature (ISS) (n=22) or obesity (n=23). The coding exons of both ghrelin and GHSR genes were screened for mutations by sequencing. RESULTS: Seven different sequence changes were identified in GHSR, two of them novel and five described previously. One previously described sequence change (p.L72M) in the ghrelin gene was identified in five patients; however, the same variant was identified at a higher rate in controls. A high rate of sequence changes was shown in ghrelin and its receptor, GHSR, in our population, but none of these changes affected the coding region of the protein. CONCLUSIONS: Despite the major role of ghrelin in growth and appetite regulation, our results indicate that mutations in ghrelin and GHSR do not explain short stature and weight regulation disorders in children in our population.

The coexistence of a novel inactivating mutant thyrotropin receptor allele with two thyroid peroxidase mutations: a genotype-phenotype correlation.

CONTEXT: TSH receptor (TSHR) and thyroid peroxidase (TPO) gene mutations occur independently. This is the first report of their coexistence in the same individuals. OBJECTIVES: The objective of the study was to evaluate the genotype-phenotype correlations when mutations in both genes are present alone or together in the same individual. PATIENTS AND METHODS: Thirty subjects from an extended Arab kindred underwent clinical investigation and molecular studies of the mutant TSHRs. RESULTS: A novel mutant TSHR was identified, involving four nucleotides at three sites on the same allele, c.267G>T (L89L), c.269/270AG>CT (Q90P), and c.790C>T (P264S). In addition, two known TPO gene mutations, G493S and R540X, were identified. Thirteen heterozygotes for the mutant TSHR allele had mild hyperthyrotropinemia. In nine of theses, the coexistence of a TPO mutation in one allele did not magnify the hyperthyrotropinemia. Homozygotes for the mutant TSHR and a compound heterozygote for the TPO mutations presented frank hypothyroidism. In vitro studies showed increasing loss of function for Q90P less than P264S less than Q90P/P264S TSHR mutants, the latter being that expressed in the subjects under investigation. The two interchangeably used WT TSHR vectors, L87 and V87, although functionally identical, differed in structure and function in the presence of the Q90P mutation. CONCLUSIONS: TSHR and TPO gene mutations were identified alone and together in individuals of a consanguineous kindred. Homozygotes for the TSHR and a compound heterozygote for the TPO mutations were hypothyroid. The mild hyperthyrotropinemia of heterozygotes for the mutant TSHR allele was not aggravated by the coexistence of a TPO defect in one allele.

Can auxology, IGF-I and IGFBP-3 measurements followed by MRI and genetic tests replace GH stimulation tests in the diagnosis of GH deficiency in children?

BACKGROUND/AIMS: GH levels < 10 ng/ml in response to two different GH stimulation tests (GHSTs) are traditionally used to identify children with GH deficiency (GHD). Since GHSTs are imprecise, other diagnostic tools have been proposed. We assessed whether auxology, IGF-I and IGFBP-3 measurements followed by brain MRI and genetic analysis can replace the current diagnostic approach. METHODS: Fifty-three children diagnosed with GHD by two different GHSTs. GH-1 gene was sequenced. RESULTS: At presentation, 17% of patients were with height above -1.5 SD and 28% above -2.0 SD; 50% had IGF-1 concentration above -1.5 SD and 58% above -2.0 SD; 59% had pituitary anomalies demonstrated by MRI. Fourteen patients harbored the heterozygous R183H mutation, one patient had the N47D mutation and one had a novel F25Y mutation in GH-1. Using cut-off levels of -1.5 SD for height, IGF-I and IGFBP-3 excluded the diagnosis of GHD in 17, 68 and 79% of the children, respectively; a cut-off of -2 SD excluded 28, 88 and 96%, respectively. Further brain MRI and genetic tests excluded 81-96% and 96-100%, respectively, of children currently diagnosed with GH. CONCLUSION: Use of the tested approach, which avoids carrying out two GHSTs, would exclude most children currently diagnosed with GHD. Until better tools become available, we recommend identifying GHD in children by an integrated approach combining phenotype, auxological parameters, hormonal measurements and two separate GHSTs, with MRI and genetic tests to support the diagnosis.

Non-transferrin-bound labile plasma iron and iron overload in sickle-cell disease: a comparative study between sickle-cell disease and beta-thalassemic patients.

BACKGROUND: Blood transfusions are the standard of care in b thalassemia and transfusions are also indicated in sickle cell disease (SCD) patients with hypersplenism, recurrent vaso-occlusive crises and for stroke prevention. Iron overload caused by blood transfusions in thalassemia and in SCD may affect morbidity and mortality. Recent studies of iron overload in SCD suggest that the biologic features of SCD and the chronic inflammatory state may protect SCD patients from iron damage. DESIGNS AND METHODS: In view of the controversy regarding the effect of iron overload in patients with SCD we studied the iron status, including non-transferrin bound iron (NTBI) and labile plasma iron (LPI) levels in a cohort of 36 SCD patients and compare the results with 43 thalassemia patients. RESULTS: Our results indicate that none of the SCD patients had clinical symptoms of iron overload. Only two SCD patients had NTBI values in the gray zone (0.4 units) and none had positive values. By contrast, 14 patients with thalassemia major and three with thalassemia intermedia had NTBI values above 0.6, level that are in the positive pathological range. Similarly, four thalassemia patients, but only one SCD patient had positive LPI levels. CONCLUSIONS: The parameters of iron status in SCD patients, even after frequent transfusions are different when compared to patients with thalassemia. The low NTBI and LPI levels found in patients with SCD are in keeping with the absence of clinical signs of iron overload in this disease.

Clinical significance of the parental origin of the X chromosome in turner syndrome.

CONTEXT: The phenotype in Turner syndrome (TS) is variable, even in patients with a supposedly nonmosaic karyotype. Previous work suggested that there were X-linked parent-of-origin effects on the phenotype. HYPOTHESIS: The TS phenotype is influenced by the parental origin of the missed X chromosome. DESIGN: This was a multicenter prospective study of TS patients and both their parents, determining parental origin of the X-chromosome, and characterizing the clinical phenotype. PATIENTS AND METHODS: Eighty-three TS patients and their parents were studied. Inclusion criteria were TS with karyotype 45,X or 46Xi(Xq). Four highly polymorphic microsatellite markers on the X-chromosome DMD49, DYSII, DXS1283, and the androgen receptor gene and three Y chromosome markers, SRY, DYZ1, and DYZ3. OUTCOME MEASURES: The study determined the correlation between the parental origin of the X chromosome and the unique phenotypic traits of TS including congenital malformations, anthropometry and growth pattern, skeletal defects, endocrine traits, education, and vocation. RESULTS: Eighty-three percent of 45,X retained their maternal X (X(m)), whereas 64% 46Xi(Xq) retained their paternal X (X(p), P < 0.001). Kidney malformations were exclusively found in X(m) patients (P = 0.030). The X(m) group had lower total and low-density lipoprotein cholesterol (P < 0.003), and higher body mass index sd score (P = 0.030) that was not maintained after GH treatment. Response to GH therapy was comparable. Ocular abnormalities were more common in the paternal X group (P = 0.017), who also had higher academic achievement. CONCLUSIONS: The parental origin of the missing short arm of the X chromosome has an impact on overweight, kidney, eye, and lipids, which suggests a potential effect of an as-yet-undetermined X chromosome gene imprinting.

Neuroendocrine phenotype analysis in five patients with isolated hypogonadotropic hypogonadism due to a L102P inactivating mutation of GPR54.

CONTEXT: Loss of function of the G protein-coupled receptor of kisspeptins (GPR54) was recently described as a new cause of isolated hypogonadotropic hypogonadism. In vivo studies performed in several species have confirmed the major role of kisspeptins in neuroendocrine regulation of the gonadotropic axis and therefore sexual maturation. OBJECTIVE: The objective of this study was to specify the exact contribution of kisspeptins and GPR54 to the initiation of puberty in humans. DESIGN: Detailed neuroendocrine descriptions were performed in five patients with isolated hypogonadotropic hypogonadism bearing a new GPR54-inactivating mutation. RESULTS: A homozygous mutation (T305C) leading to a leucine substitution with proline (L102P) was found in the five affected patients. This substitution completely inhibited GPR54 signaling. Phenotypic analysis revealed variable expressivity in the same family, either partial or complete gonadotropic deficiency. LH pulsatility analysis showed peaks with normal frequency but low amplitude. Repeated GnRH tests performed between 12 and 21 yr of age in one affected male revealed progressive changes in pituitary response from an early pubertal to an almost full pubertal pattern. Double GnRH test stimulations performed at a 120-min interval showed reduced dynamic pituitary response in GPR54-mutated patients. CONCLUSION: GPR54 inactivation does not impede neuroendocrine onset of puberty; rather, it delays and slows down pubertal maturation of the gonadotropic axis. The L102P loss of function mutation in GPR54 results in a more quantitative than qualitative defect of gonadotropic axis activation.

Hyperandrogenism in carriers of CYP21 mutations: the role of genotype.

OBJECTIVE: It has been hypothesized that carriers of CYP21 mutations are at increased risk of developing clinically evident hyperandrogenism. In the present study, we assessed the risk for symptoms of androgen excess in carriers of CYP21 gene mutations and the effect of different mutations on phenotype. DESIGN: All subjects underwent clinical evaluation, ACTH stimulation testing, and molecular analysis of the CYP21 gene. PATIENTS: One hundred and eighty-seven subjects were included in the study. Five groups were defined according to genotype: A, 38 patients with classical-congenital adrenal hyperplasia (CAH); B, 16 patients with non classical CAH; C, 66 family member carriers; D, 24 children and adolescents with symptoms suggestive of hyperandrogenism who were found to be heterozygous and E, 43 subjects with androgen excess symptoms who had normal genotype. MEASUREMENTS: Cortisol and 17-hydroxyprogesterone (17OHP) were measured basally and 60 min after ACTH stimulation. Analysis of seven common mutations of the CYP21 gene, which collectively cover 95% of the mutations in the Israeli population, was performed. The hormonal results were correlated with the genotype. RESULTS: The symptomatic carriers had a significantly higher rate of the mild mutation V281L compared with the family members (58% vs. 22%) and significantly higher levels of ACTH-stimulated 17OHP (mean 37.2 and 21 nmol/l, respectively; P = 0.025). Higher values of peak 17OHP levels were found in the carriers of the V281L mutation compared with carriers of other mutations (P = 0.025). Stimulated 17OHP levels were significantly higher in carriers compared with normal genotype subjects (P < 0.0001). CONCLUSIONS: Our findings are the first to show that there is increased risk of androgen excess in carriers of CYP21 mutations and that the risk is related to genotype. Carriers for the mild, V281L mutation, are at higher risk of symptoms of androgen excess than carriers of the severe mutations. It appears that the variable phenotypes can be at least partially attributed to the degree of impairment of enzyme activity in different mutations. The severe consequences of hyperandrogenism in some of the carrier subjects indicate the need for long-term follow-up in these patients.

Secondary diabetes mellitus: late complication of glycogen storage disease type 1b.

We report a 22 year-old male with glycogen storage disease type 1 (GSD-1) who developed diabetes mellitus secondary to pancreatic islet beta-cell insufficiency. Diabetes mellitus should be considered among the late complications of GSD-1. The pathogenesis of the conversion, from a disease characterized by hypoglycemia to a disease dominated by hyperglycemia, is discussed.

Extrapancreatic autoimmune manifestations in type 1 diabetes patients and their first-degree relatives: a multicenter study.

OBJECTIVE: To investigate the prevalence of autoimmune diseases in young patients (probands) with type 1 diabetes and their first-degree relatives, and to determine the spectrum of extrapancreatic manifestations in these subjects. RESEARCH DESIGN AND METHODS: The study population included 109 probands age 13 +/- 4.9 years and 412 first-degree relatives age 28.7 +/- 16.2 years. The prevalence rates of autoimmune thyroiditis and celiac disease were determined in all probands and in 100 of the 412 first-degree relatives. Control groups included 78 subjects age 14.9 +/- 10.4 years for the prevalence of autoimmune thyroiditis and 120,000 youth ages 16-17 years for the prevalence of celiac disease. Thyroiditis and celiac disease were diagnosed by abnormally high thyroid peroxidase (TPO), thyroglobulin (TG), antigliadin, and antiendomysial antibody titers. Celiac was confirmed by biopsy. A questionnaire was used to interview probands and relatives to determine the spectrum of autoimmune manifestations. RESULTS: The prevalence of autoimmune thyroiditis determined by high TPO and/or TG titers was 27 and 25% for probands and relatives, respectively. These rates were higher than those for control subjects (P < 000.1). The prevalence of celiac disease among probands and screened relatives was 8.3 and 6%, respectively. These rates were higher than those for control subjects and the 312 family members interviewed only (0.1 and 0.3%, respectively; P < 0.0001). Interviews of participants revealed a wide range of associated autoimmune diseases. The risk of developing an autoimmune disease was higher (P < 0.001) in families with a proband who had an additional autoimmune manifestation. CONCLUSIONS: Screening for autoimmune thyroiditis and celiac disease should be performed in patients with type 1 diabetes and their first-degree relatives, especially when the probands have an additional autoimmune manifestation.