A Novel De novo Heterozygous Mutation in the SON Gene Associated with Septo-optic Dysplasia: A New Phenotype.

Septo-optic dysplasia (SOD) syndrome is a rare congenital disorder characterized by a classic triad of optic nerve/chiasm hypoplasia, agenesis of septum pellucidum and corpus callosum, and hypoplasia of the hypothalamic-pituitary axis.Herein, we report the clinical case of 2-year-old boy presenting with psychomotor delay, nystagmus, congenital hypothyroidism, and a clinically relevant growth delay. The neuroradiological examination showed partial segmental agenesis of the corpus callosum, agenesis of the septum pellucidum, optic nerve hypoplasia, and a small pituitary gland with a small median pituitary stalk. A whole-exome sequencing analysis detected a novel heterozygous de novo variant c.1069_1070delAG in SON, predicted as likely pathogenic.To date, SON pathogenic variants have been described as responsible for Zhu-Tokita-Takenouchi-Kim (ZTTK) syndrome, a multisystemic neurodevelopmental disorder mainly characterized by intellectual disability, facial dysmorphisms, visual abnormalities, brain malformations, feeding difficulties, and growth delay. The herein described case is the first recognized clinic-radiological occurrence of SOD syndrome with hypothalamic-pituitary dysfunction in a patient carrying a SON gene variant, considered responsible of ZTTK syndrome, suggesting a possible relationship between SOD and SON gene alterations, never described so far, making the search for SON gene mutations advisable in patients with SOD.

A frequent oligogenic involvement in congenital hypothyroidism.

Congenital hypothyroidism (CH), the most frequent form of preventable mental retardation, is predicted to have a relevant genetic origin. However, CH is frequently reported to be sporadic and candidate gene variations were found in <10% of the investigated patients. Here, we characterize the involvement of 11 candidate genes through a systematic Next Generation Sequencing (NGS) analysis. The NGS was performed in 177 unrelated CH patients (94 gland-in-situ; 83 dysgenesis) and in 3,538 control subjects. Non-synonymous or splicing rare variants (MAF < 0.01) were accepted, and their functional impact was predicted by a comprehensive bioinformatic approach and co-segregation studies. The frequency of variations in cases and controls was extended to 18 CH-unrelated genes. At least one rare variant was accepted in 103/177 patients. Monogenic recessive forms of the disease were found in five cases, but oligogenic involvement was detected in 39 patients. The 167 variations were found to affect all genes independently of the CH phenotype. These findings were replicated in an independent cohort of additional 145 CH cases. When compared to 3,538 controls, the CH population was significantly enriched with disrupting variants in the candidate genes (P = 5.5 × 10-7), but not with rare variations in CH-unrelated genes. Co-segregation studies of the hypothyroid phenotype with multiple gene variants in several pedigrees confirmed the potential oligogenic origin of CH. The systematic NGS approach reveals the frequent combination of rare variations in morphogenetic or functional candidate genes in CH patients independently of phenotype. The oligogenic origin represents a suitable explanation for the frequent sporadic CH occurrence.

Mild TSH resistance: Clinical and hormonal features in childhood and adulthood.

OBJECTIVE: Mutations in TSH receptor (TSHR) are associated with TSH resistance, a genetic defect characterized by a heterogeneous phenotype ranging from severe hypothyroidism to subclinical hypothyroidism (SCH). We assessed the clinical and hormonal pattern of TSHR variants in a series of pediatric patients, and the long-term outcome of growth, biochemical measurements of metabolism, and neuropsychological functions in TSHR mutations carriers. DESIGN: Observational, retrospective study. PATIENTS: Thirty four children (age 7 days to 11 years) and 18 adult carriers of TSHR variants. MEASUREMENTS: The TSHR gene was sequenced by PCR-amplified direct sequencing in 111 pediatric patients with slight to moderate elevation of TSH and normal FT4 levels. The study focused on the: auxological and biochemical parameters, thyroid ultrasound, bone age, bone mineral density (BMD), and intellectual outcome (IQ) were collected during the long follow-up (1-15 years). RESULTS: Seventeen different TSHR variants (eight novel) were identified in 34 of the 111 pediatric patients, with a high prevalence of familial cases (27/34). Neonatal screening for congenital hypothyroidism was positive in half of the TSHR carriers. Growth, IQ, BMD, and biochemical parameters were normal in all subjects. Twenty patients received L-T4 replacement therapy, in all cases before genetic analysis. After re-evaluation, six patients resumed L-T4 therapy: they were compound heterozygous, or single heterozygous and with associated conditions at risk of thyroid impairment (SGA). No adults presented clinical features consistent with impaired thyroid function. CONCLUSIONS: Children carriers of TSHR variants, regardless of L-T4 treatment, show regular growth and neuropsychological development, with no evident biochemical and US alterations.

Evolution of thyroid function in preterm infants detected by screening for congenital hypothyroidism.

OBJECTIVE: To determine the evolution of congenital hypothyroidism in preterms and the clinical features of permanent forms. STUDY DESIGN: We retrospectively evaluated 24 preterm children detected by newborn screening for congenital hypothyroidism: first screening with blood-thyroid stimulating hormone cutoff ≥10 mU/L and second screening with blood-thyroid stimulating hormone cutoff ≥5 mU/L. After the age of 2 years, patients with eutopic thyroid had diagnostic reevaluations, including thyroid function testing and thyroid ultrasonography after L-thyroxine therapy withdrawal. RESULTS: The first screening identified 21.7% of patients with thyroid stimulating hormone elevation, and the second screening identified 73.9% of patients. One patient (4.4%) was identified with a third screening test; 21 patients had an eutopic thyroid and 3 patients a thyroid dysgenesis. At reevaluation, 5 patients (23.8%) showed permanent hypothyroidism (serum-thyroid stimulating hormone [s-TSH] >10 mU/L) resulting in the need to reintroduce therapy, 5 patients (23.8%) showed persistent hyperthyrotropinemia (s-TSH 5-10 mU/L), and 11 infants (52.4%) transient hypothyroidism (s-TSH <5 mU/L). The main clinical features of patients affected by permanent hypothyroidism were 1 case of assisted reproduction, 2 twins, 2 small for gestational age, 1 maternal thyroiditis, and 2 patients with malformations/syndromes. CONCLUSIONS: Premature birth is a significant risk for congenital hypothyroidism with eutopic thyroid. In preterm infants, the evolution of congenital hypothyroidism remains difficult to predict. Our data emphasizes the high incidence of transient hypothyroidism in preterm infants, and the importance of diagnostic reevaluation to determine the definitive diagnosis.

Graves disease in children: thyroid-stimulating hormone receptor antibodies as remission markers.

OBJECTIVE: To evaluate clinical and biochemical features of 115 children (98 female, mean age 11.3 ± 3.5 years) with Graves disease to identify possible determinants of remission. STUDY DESIGN: We defined as positive outcome the improvement of clinical features and restoration of euthyroidism or induction of hypothyroidism after antithyroid drug (ATD) therapy and as negative outcome hyperthyroidism persistent over 2 years of ATD therapy or relapsed after ATD withdrawal. RESULTS: Thirty-eight children (33%) had remission after 2 years of ATD therapy. The absence of goiter at diagnosis was correlated with a better outcome. Median thyroid-stimulating hormone receptor antibody (TRAb) values at diagnosis were significantly lower in patients with a positive outcome (P = .031). We found a significant relationship between the time required for TRAb normalization and the patient outcome; TRAb normalization within 1 year from time of Graves disease diagnosis was significantly more common among patients with a positive outcome (P < .0001), and the mean time for TRAb normalization was significantly shorter in patients with a positive outcome (1.3 ± 0.8 years) compared with that observed in patients with a negative outcome (2.5 ± 2.7 years, P = .026). CONCLUSIONS: Although no clinical variable investigated is constantly associated with a definite outcome, the absence of goiter at the diagnosis may be associated with a better outcome. The most relevant predictor of Graves disease outcome was serum level; TRAb at time of Graves disease diagnosis less than 2.5 times the upper reference limit, TRAb normalization during ATD, and TRAb normalization timing each may predict positive outcomes. These results may have a role in the empiric clinical management of pediatric patients with Graves disease.

Serum thyrotropin concentration in children with isolated thyroid nodules.

OBJECTIVE: To investigate the correlation between serum thyroid-stimulating hormone (TSH) concentration and nodule nature in pediatric patients with thyroid nodules, with the aim of identifying a marker able to differentiate benign and malignant nodules. STUDY DESIGN: This was a retrospective analysis of serum TSH concentrations in a multicentric case series of 125 pediatric patients with benign and malignant thyroid nodules. RESULTS: Of the 125 patients, 99 had benign thyroid nodules and 26 had differentiated thyroid cancer (24 papillary and 2 follicular). Final diagnosis was based on surgery in 57 cases and on a benign cytology plus clinical follow-up in 68 cases. Serum TSH concentration was significantly higher in patients with thyroid cancer compared with those with benign nodules (3.23 ± 1.59 mU/L vs 1.64 ± 0.99 mU/L; P < .001). Binary logistic regression analysis revealed that serum TSH was the sole predictor of malignancy (P < .001). Dividing the patient cohort into 5 groups based on serum TSH quintiles (TSH cutoffs 0.40, 1.00, 1.50, 1.80, and 2.80 mU/L), we observed that cancer prevalence increased in parallel with serum TSH (P < .001), with respective rates of 0%, 4%, 16%, 32%, and 52% in the 5 quintile groups. CONCLUSION: Because cases with malignant nodules are most likely seen in the upper normal serum TSH range (ie, >2.8 mU/L), serum TSH concentration can serve as a predictor of thyroid cancer in pediatric patients with thyroid nodules and can inform the decision of when to submit patients to further investigation by cytology.

Case Report - Multinodular goiter in a patient with Congenital Hypothyroidism and Bannayan-Riley-Ruvalcaba syndrome: the possible synergic role of TPO and PTEN mutation.

We report the case of a paediatric female patient affected by Bannayan-Riley-Ruvalcaba syndrome (BRRS) and congenital hypothyroidism (CH) with homozygous mutation of the TPO gene. She underwent total thyroidectomy at the age of seven years because of the development of a multinodular goiter. BRRS patients present an increased risk of benign and malignant thyroid disease since childhood because of inactivating mutation of PTEN, an onco-suppressor gene. Instead, homozygous mutations in the TPO gene can be associated with severe forms of hypothyroidism with goiter; previous studies have described cases of follicular and papillary thyroid cancer in CH patients with TPO mutation despite a perfectly controlled thyroid function with Levothyroxine therapy. To our knowledge, this is the first case that describes the possible synergic role of coexisting mutation of both TPO and PTEN in the development of multinodular goiter underlining the importance of a tailored surveillance program in these patients, especially during childhood.

Perinatal asphyxia and hypothermic treatment from the endocrine perspective.

Introduction: Perinatal asphyxia is one of the three most important causes of neonatal mortality and morbidity. Therapeutic hypothermia represents the standard treatment for infants with moderate-severe perinatal asphyxia, resulting in reduction in the mortality and major neurodevelopmental disability. So far, data in the literature focusing on the endocrine aspects of both asphyxia and hypothermia treatment at birth are scanty, and many aspects are still debated. Aim of this narrative review is to summarize the current knowledge regarding the short- and long-term effects of perinatal asphyxia and of hypothermia treatment on the endocrine system, thus providing suggestions for improving the management of asphyxiated children. Results: Involvement of the endocrine system (especially glucose and electrolyte disturbances, adrenal hemorrhage, non-thyroidal illness syndrome) can occur in a variable percentage of subjects with perinatal asphyxia, potentially affecting mortality as well as neurological outcome. Hypothermia may also affect endocrine homeostasis, leading to a decreased incidence of hypocalcemia and an increased risk of dilutional hyponatremia and hypercalcemia. Conclusions: Metabolic abnormalities in the context of perinatal asphyxia are important modifiable factors that may be associated with a worse outcome. Therefore, clinicians should be aware of the possible occurrence of endocrine complication, in order to establish appropriate screening protocols and allow timely treatment.

Difficult treatment of consumptive hypothyroidism in a child with massive parotid hemangioma.

Consumptive hypothyroidism is a rare condition related to massive infantile hemangiomas producing an excess of the thyroid-hormone-inactivating enzyme type 3 iodothyronine deiodinase. We report the first case of consumptive hypothyroidism secondary to a large parotid hemangioma, highlighting the difficulties in selecting an adequate therapeutic strategy. The affected child was initially referred to our center for congenital hypothyroidism with a hypoplastic thyroid gland. L-Thyroxine (L-T4) replacement therapy was started at seven days of life. In the following weeks, the hemangioma rapidly increased in volume and the child developed severe hypothyroidism refractory to high doses of L-T4 therapy. The concentration of reverse triiodothyronine was elevated, suggesting that the underlying cause was an excessive conversion of thyroid hormones by high type 3 iodothyronine deiodinase levels in the tumor. Corticosteroid treatment showed only partial benefit. Introduction of propranolol instead led to normalization of thyroid hormones along with a dramatic involution of the hemangioma.

Surgical management of pediatric Graves' disease: an effective definitive treatment.

PURPOSE: The optimal treatment for pediatric Graves' disease (GD) is controversial. Antithyroid drugs are often used initially, but they are associated with a high failure rate. Therefore alternative therapies have become important. In the present study, we analyze our institution's experience regarding the safety and efficacy of thyroid surgery among pediatric patients with GD. METHODS: This is a retrospective chart review of 27 pediatric patients (age ≤ 18 years) with GD who underwent thyroid surgery between 1991 and 2009 at a single academic Institution. We recorded preoperative, intraoperative, and short-term postoperative data. RESULTS: All 27 patients were initially treated with thionamides. The high rate of hyperthyroidism relapse after discontinuation of medical treatment, age < 5 years, adverse reaction to medical therapy, severe ophthalmopathy, and patient preference justified the final decision to proceed with surgery as definitive therapy. All patients underwent total thyroidectomy. We had no mortality; surgical complications were rare: 4 (14.8 %) cases of transient hypocalcemia, 1 (3.7 %) of permanent hypocalcemia, 3 (11.1 %) of transient RLN neuropraxia, and 2 (7 %) of keloid scar. No bleeding, permanent RLN palsy or relapse hyperthyroidism were reported. CONCLUSIONS: Surgical therapy for pediatric GD performed by experienced thyroid surgeons is a safe, definitive and cost-effective treatment.

Effect of initial levothyroxine dose on neurodevelopmental and growth outcomes in children with congenital hypothyroidism.

Objectives: We designed a multicentre open prospective randomized trial to evaluate the risk-benefit profile of two different initial treatment schemes with levothyroxine (L-T4), 10-12.5 µg/kg/day vs 12.6-15 µg/kg/day, on growth and neurodevelopmental outcomes in children with congenital hypothyroidism (CH) detected by neonatal screening to identify the best range dose to achieve optimal neurocognitive development. Design patients and methods: Children detected by neonatal screening were randomly assigned to receive an initial L-T4 dose of 10-12.5 µg/kg/day (Low) or 12.6-15 µg/kg/day (High). All patients underwent periodical clinical examination with measurement of growth parameters and measurement of TSH and FT4. Neurocognitive development was evaluated at the age of 24 months using Griffiths Mental Development Scales (GMDS) and cognitive and behavioral assessment was performed at 48 months of age using Wechsler Preschool and Primary scale of Intelligence (WIPPSI-III). The study was registered with clinicaltrials.gov (NCT05371262). Results: Treatment schemes below or above 12.5 µg/kg/day were both associated with rapid normalization of TSH and thyroid hormone levels in most patients with no differences in the risk of over- and under-treatment episodes in the first months of life. Growth parameters were normal and comparable between the two groups. Developmental quotients at 24 months of age were normal in both groups (Low 100.6 ± 15.5 vs High 96.9 ± 16.6). Likewise, at 4 years of age IQ and subtest scores were comparable between patients from Low and High (Total IQ 104.2 ± 11.4 vs 101.0 ± 20.3, Verbal IQ 103.9 ± 11.5 vs 98.7 ± 15.1, Performance IQ 105.3 ± 10.4 vs 100.3 ± 19.8). 6/45 CH patients (13.3%) showed a total IQ below 85 (73.7 ± 5.9) regardless of age at diagnosis, L-T4 starting dose, time of FT4 and TSH normalization and episodes of over and undertreatment. Worse socioeconomic status and delayed bone age at diagnosis were the only predictors of an increased risk of having suboptimal IQ at 24 and IQ at 48 months. Conclusions: Our results indicate that initial treatment with L-T4, 10-12.5 µg/kg/day vs 12.6-15 µg/kg/day, are both associated with normal growth and neurodevelopmental outcomes in children with CH detected by neonatal screening. Further studies with a long-term follow-up on a larger number of patients are needed to confirm these results. Clinical trial registration: https://clinicaltrials.gov/ct2/show/NCT05371262?term=NCT05371262&draw=2&rank=1 identifer NCT05371262.

"Thyroid nodular disease and PTEN mutation in a multicentre series of children with PTEN hamartoma tumor syndrome (PHTS)".

PURPOSE: To report the incidence of 4-12% of differentiated thyroid cancer (DTC) and up to 50% of benign thyroid nodular disease and to describe nodular thyroid disease in a multicentre pediatric population with PTEN mutations. METHODS: Retrospective data of pediatric patients with PTEN mutations collected from tertiary Departments of Pediatric Endocrinology of Turin, Milan and Genua, Italy, in the period 2010-2020. RESULTS: Seventeen children with PTEN mutations were recruited in the study. Thyroid involvement was present in 12/17 (70.6%) subjects, showing a multinodular struma in 6/17 (35.3%), nodules with benign ultrasound features in 5/17 (29.4%) and a follicular adenoma in 1/17 (6%). No correlation was found between thyroid disease and gender, puberty, vascular manifestations, delayed development, or brain MRI abnormalities, while multiple lipomas were associated with thyroid disease (p = 0.03), as was macrocephaly. Standard Deviation (SD) score head circumference was 4.35 ± 1.35 cm in subjects with thyroid disease, 3 ± 0.43 cm (p = 0.02) in the group without thyroid disease. Thyroid involvement was present in all subjects with mutations in exon 6 (4/4) and exon 8 (3/3) of the PTEN gene (p = 0.02). CONCLUSION: In the presented cohort, benign thyroid disorders were prevalent, with no evidence of DTC. A correlation was found between thyroid lesions and head circumference and the occurrence of multiple lipomas. Future studies in larger cohorts should assess whether risk stratification is needed when recommending surveillance strategies in children or young adolescents with PTEN hamartoma syndrome.

Newborn Screening for Congenital Hypothyroidism: the Benefit of Using Differential TSH Cutoffs in a 2-Screen Program.

CONTEXT: Analysis of a 2-screen program for congenital hypothyroidism (CH) was performed using differential dried-blood spot thyrotropin (bTSH) cutoffs of 10 mU/L at first screening (all infants) and 5 mU/L at second screening (selected infants). OBJECTIVES: This work aimed to characterize CH infants identified by the second screening and compare infants with bTSH of 5.0 to 9.9 and 10 mU/L or greater on second screening. DESIGN AND PATIENTS: Maternal and neonatal clinical features were retrospectively analyzed for 119 CH babies detected on the second screen in the Lombardy region of Italy, 2007 to 2014. RESULTS: Fifty-two (43.7%) of the 119 CH neonates showed bTSH values ranging from 5.0 to 9.9 mU/L at the second screening (low bTSH group) and 67 (56.3%) bTSH of 10.0 mU/L or greater (high bTSH group). The frequency of thyroid dysgenesis and eutopic gland was similar in both groups, as was the frequency of permanent and transient CH. Moreover, a high frequency of extrathyroidal malformations was found in both groups. The percentage of preterm infants (57.7% vs 23.9%, P < .001) and infants admitted to the neonatal intensive care unit (50.0% vs 17.9%, P < .001) was significantly higher in the low vs the high bTSH group. In addition, maternal treatment with glucocorticoids in pregnancy was significantly more frequent in the low bTSH group than in the high bTSH group (11.5% vs 1.5%, P = .042), as well as maternal hypothyroidism and/or goiter (26.9% vs 10.4%, P = .036). CONCLUSIONS: This study has demonstrated that a lower TSH cutoff at the second screening can detect additional cases of CH and that a second bTSH cutoff of 5.0 mU/L is appropriate for identifying preterm newborns and babies with associated risk factors.

Treatment of congenital hypothyroidism: comparison between L-thyroxine oral solution and tablet formulations up to 3 years of age.

OBJECTIVE: Oral solution and tablet formulations of levothyroxine (L-T4) are both used in the treatment of congenital hypothyroidism (CH). However, few studies and with a limited follow-up period have been published comparing these two formulations in children. DESIGN: The aim of this multicenter study was to compare the effectiveness of L-T4 oral solution (with ethanol as excipient) and tablet formulation in children with CH up to 3 years of age. METHODS: Children diagnosed with CH between 2006 and 2015 were enrolled and divided into two groups according to the L-T4 formulation used: solution in drops (group D) or tablets (group T). Auxological parameters, thyroid-stimulating hormone (TSH) and free thyroxine (FT4) values and L-T4 dose were collected at diagnosis and at 15 days, 1, 3, 6, 12, 24 and 36 months of treatment. The developmental quotient (DQ) at 1 and 3 years of age was evaluated using Griffiths' Scale. RESULTS: In this study, 254 children were enrolled among which 117 were treated with solution and 137 with tablets. Auxological parameters, dose and thyroid function values at diagnosis, 3, 6, 12, 24, 36 months were not significantly different. TSH at 15 days (P = 0.002) and 1 month (P = 0.009) was significantly reduced in group D. At 2-year follow-up, median TSH was significantly lower in group T (P = 0.03). No statistical difference was detected between the median DQ; however, group D showed lower values in the language subscale at 12 months and in eye-hand coordination at 36 months. CONCLUSIONS: Both therapeutic strategies are effective in the treatment of CH. A higher risk of overtreatment in the first months of therapy seems to be associated with oral solution L-T4; therefore, a different strategy should be considered when starting and adjusting the dose. No negative effects on cognitive development were observed. The data obtained are encouraging but long-term follow-up is needed.

COVID-19 infection in a paucisymptomatic infant: Raising the index of suspicion in epidemic settings.

Few children have been reported to have been affected by novel coronavirus disease 2019 (COVID-19); it is unclear whether children are less likely to be infected or rather display fewer symptoms. We present the case of a 32-day-old boy infected by COVID-19 that presented with an upper air way infection which resolved spontaneously and did not require any therapy. We argue that in epidemic settings children presenting with any mild symptom potentially attributable to COVID-19 should be considered contagious until proven otherwise, and that management must be guided by clinical conditions.

Influence of Hashimoto Thyroiditis on the Development of Thyroid Nodules and Cancer in Children and Adolescents.

It is unclear whether patients with Hashimoto thyroiditis (HT) are predisposed to develop thyroid nodules and/or thyroid cancer. The objective of our study was therefore to assess the prevalence of thyroid nodules and/or cancer in patients with HT and to look for possible prognostic factors. A retrospective survey of 904 children/adolescents with HT (709 females, 195 males) regularly followed in nine Italian centers of pediatric endocrinology was performed. Median period of follow-up was 4.5 years (1.2 to 12.8 years). We evaluated free T4, TSH, thyroid peroxidase antibody (TPOAb), thyroglobulin antibodies, and thyroid ultrasound yearly. One hundred seventy-four nodules were detected, with an annual incidence rate of 3.5%. Ten nodules were malignant (8 papillary and 2 papillary follicular variant), giving a 5.7% prevalence of cancer among patients with nodules. The severity of hypoechogenity at ultrasound, TPOAb, and free T4 serum concentrations were predictive for the appearance of new nodules. Furthermore, a positive correlation was observed between TPOAb titer and the development of thyroid cancer. In conclusion, HT seems to influence the development of thyroid nodules, but not cancer in children and adolescents.

Neonatal Screening for Congenital Hypothyroidism: What Can We Learn From Discordant Twins?

CONTEXT: Newborn screening program for congenital hypothyroidism (CH) adopting rescreening in at-risk neonates. OBJECTIVES: To estimate the concordance rate for CH in twin pairs discordant at the first screening; to verify whether long-term follow-up of healthy cotwins belonging to CH discordant pairs may be useful to diagnose thyroid hypofunction during development; to evaluate the importance of genetic and environmental influences on liability to permanent and transient CH. DESIGN AND PATIENTS: Forty-seven screening discordant twin pairs were investigated. Proband was defined as the twin in the pair with a positive test at the first screening and a confirmed diagnosis of CH. RESULTS: Seven screening discordant twin pairs became concordant for CH within the first month of life (pairwise concordance of 14.9%) because seven screening negative cotwins showed high TSH values when retested. During long-term follow-up (range, 3 to 21 years), hypothyroidism was diagnosed in two monozygotic screening negative cotwins at the age of 9 months and 12 years, respectively. Furthermore, the twin analysis showed that 95% of liability to transient CH was explained by genetic factors and 5% by environmental (unshared) factors, whereas 64% of phenotypic variance of permanent CH was explained by common environmental factors (shared during the fetal life) and 36% by unshared environmental factors. CONCLUSIONS: This study showed that the introduction of rescreening permits the diagnosis of CH in a greater number of twins. It also showed the importance of long-term follow-up in both twins in the pair, and the role of nongenetic factors in the etiology of permanent CH.

Biallelic inactivation of the dual oxidase maturation factor 2 (DUOXA2) gene as a novel cause of congenital hypothyroidism.

CONTEXT: Dual oxidase 2 (DUOX2) is the catalytic core of the H(2)O(2) generator crucial for the iodination of thyroglobulin in thyroid hormone synthesis. DUOX2 deficiency produces congenital hypothyroidism (CH) in humans and mice. We recently cloned a novel gene, the product of which (dual oxidase maturation factor 2; DUOXA2) is required to express DUOX2 enzymatic activity. OBJECTIVE: Our objective was to identify DUOXA2 mutations as a novel cause of CH due to dyshormonogenesis. PATIENTS: Subjects included 11 CH patients with partial iodine organification defect but negative for other known genetic causes of partial iodine organification defect. RESULTS: One Chinese patient born to nonconsanguineous parents was homozygous for a nonsense mutation (p.Y246X), producing a truncated DUOXA2 protein lacking transmembrane helix 5 and the C-terminal cytoplasmic domain. The mutant protein was inactive in reconstituting DUOX2 in vitro. Pedigree analysis demonstrated recessive inheritance, because heterozygous carriers had normal thyroid function including negative results in neonatal TSH screening. One heterozygous carrier of Y246X was identified in unrelated Chinese controls (n = 92) but not in Caucasian or Japanese controls, indicating that homozygosity for Y246X could be a frequent cause of CH in Chinese. Functional studies suggest that the DUOXA2 paralog (DUOXA1) can partially compensate DUOXA2 deficiency, consistent with the proband having a milder CH phenotype than patients with biallelic DUOX2 nonsense mutations. CONCLUSIONS: We report the first mutation in DUOXA2, identified in a patient with CH and dyshormonogenic goiter. Results of our studies provide evidence for the critical role of DUOXA2 in thyroid hormonogenesis. Biallelic DUOXA2 mutations are a novel genetic event in permanent CH.

Mild Hypothyroidism in Childhood: Who, When, and How Should Be Treated?

Mild hypothyroidism, also known as subclinical hypothyroidism (SH), is biochemically defined as serum TSH levels above the upper limit of the reference range, in the presence of normal serum concentrations of total T4 and free T4 (FT4). In the neonatal period, mild hypothyroidism can be defined by the presence of a TSH value between 6 and 20 mIU/L and normal FT4 levels. After the neonatal period, SH can be defined mild if TSH ranges between 4.5 and 10 mIU/L. The management of mild hypothyroidism in childhood is challenging. The major concern is to establish whether this condition should always be considered an expression of mild thyroid dysfunction. Indeed, the effects of untreated mild hypothyroidism are still not completely defined. In the neonatal period, concern exists about neurocognitive outcome; in children, although there is no clear evidence of alterations in growth or neurocognitive development, subtle cardiovascular abnormalities have been documented. Therefore, there is still uncertainty about the need of treatment across all ages, and the management should be based on the age of the child, the etiology, and the degree of TSH elevation, as well as on other patient factors. This review updates current evidences on diagnosis and management of mild hypothyroidism in childhood.