Thyroxine-Based Screening for Congenital Hypothyroidism in Neonates with Down Syndrome

Endocrine, auxological and metabolic profile in children and adolescents with Down syndrome: from infancy to the first steps into adult life

Down syndrome (DS) is the most common chromosomal disorder worldwide. Along with intellectual disability, endocrine disorders represent a remarkable share of the morbidities experienced by children, adolescents and young adults with DS. Auxological parameters are plotted on syndrome-specific charts, as growth rates are reduced compared to healthy age- and gender-matched peers. Furthermore, children with DS are at increased risk for thyroid dysfunctions, diabetes mellitus, osteopenia and obesity compared to general population. Additionally, male individuals with DS often show infertility, while women tend to experience menopause at an overall younger age than healthy controls. Given the recent outstanding improvements in the care of severe DS-related comorbidities, infant mortality has dramatically decreased, with a current average life expectancy exceeding 60 years. Accordingly, the awareness of the specificities of DS in this field is pivotal to timely detect endocrine dysfunctions and to undertake a prompt dedicated treatment. Notably, best practices for the screening and monitoring of pediatric endocrine disorders in DS are still controversial. In addition, specific guidelines for the management of metabolic issues along the challenging period of transitioning from pediatric to adult health care are lacking. By performing a review of published literature, we highlighted the issues specifically involving children and adolescent with DS, aiming at providing clinicians with a detailed up-to-date overview of the endocrine, metabolic and auxological disorders in this selected population, with an additional focus on the management of patients in the critical phase of the transitioning from childhood to adult care.

Prospective study of thyroid function in the first year of life in infants with Down syndrome

Current American Academy of Pediatrics (AAP) Guidelines recommend monitoring thyroid function in infants with Down syndrome (DS) at birth, 6 and 12 months, and annually thereafter. This study aimed to determine whether these guidelines are optimal for early diagnosis and treatment of (subclinical) hypothyroidism. Enrolled infants with DS less than age 7 months, born at ≥ 30 weeks gestation to monitor thyroid function test (TFT). A filter paper (FP) blood sample was analyzed for TSH and total T4 at ages 2 and 4 weeks and monthly thereafter until 12 months. Subjects with abnormal FP sample and confirmatory serum TFT for hypothyroidism promptly started treatment. Subjects with thyroid dysfunction identified had thyroid antibodies measured at diagnosis and 12 months. Descriptive statistics determined average time to diagnosis of abnormal TFT. Sixteen (30%) of 54 subjects were diagnosed with a thyroid disorder, the majority with subclinical hypothyroidism (SH) and 1 with hyperthyroidism. Diagnosis occurred in 6 (11%), 9 (17%), and 12 (22.2%) infants in the first 30, 60, and 90 days of life (DOL), respectively. Eight infants had an abnormal NBS and half were diagnosed with a thyroid disorder by DOL 8 and the remainder prior to 4 months. Among subjects with a normal NBS, four were diagnosed at a mean of 104 days and three at a mean of 101 days prior to the 6-month and 12-month routine screens, respectively.  Conclusion: Based on current AAP guidelines, thyroid disorder diagnosis would have been delayed in nearly 20% of the subjects. An additional TFT screen at 1 and 3 months can lead to earlier diagnosis and treatment. What is Known: • Current American Academy of Pediatrics (AAP) Guidelines recommend thyroid function tests (TFT) in infants with Down syndrome (DS) at birth and 6 and 12 months. • Peer- reviewed retrospective studies report an increased incidence of hypothyroidism in infants with DS undetected by the newborn screen (NBS) and prior to 6 months. What is New: • This prospective study monitored TFT in infants with DS at age 2 weeks and monthly throughout the first year of life. • The findings in this study support additional TFT screens at 1 and 3 months in infants with DS.

Otolaryngologic Disease in Down syndrome

As the most common human chromosomal abnormality, Trisomy 21 is a condition that many otolaryngologists and likely all pediatric otolaryngologists will encounter during their careers. There are several considerations regarding airway obstruction, otologic conditions, anesthetic implications, and endocrine disorders that will impact the treatment of these patients. Further, there is increasing literature supporting the use of early instrumental assessment of swallowing, drug-induced sleep endoscopy at the time of first surgical intervention for sleep apnea, consideration of concurrent upper and lower airway evaluation, and early otologic management including potential surgical hearing rehabilitation.

Quantification of serum thyroid hormones using tandem mass spectrometry in patients with Down syndrome

Thyroid dysfunction is common in patients with Down syndrome (DS), the most common chromosomal disorder. Thyroid hormones (THs) are important for normal growth, neurodevelopment, and metabolism, highlighting the importance of quantifying the levels in patients with DS. However, current methods possess cross-reactivity that results in inaccuracies in quantification. We aimed at developing a new analytical method for quantifying the total 3,3',5-triiodo-l-thyronine (TT3), total 3,3',5,5'-tetraiodo-l-thyronine (TT4), 3,3',5'-triiodo-l-thyronine, and reverse T3 (rT3) levels using LC-MS/MS. Repeatability and reproducibility with coefficient of variation values of 2-9 and 3-13%, respectively, were acceptable, suggesting that the assay was suitable for measuring serum THs. We measured the serum TH levels of patients with DS but without thyroid dysfunction (age, 3-20 years) and compared the levels to those of controls (patients with idiopathic short stature; age, 3-17 years). When TH levels were summarized by age group, the serum TT4 concentrations were not significantly different between the controls and patients with DS across all age groups. Meanwhile, the serum TT3 concentrations differed according to age. In addition, the serum rT3 concentrations were significantly higher in patients with DS than in controls, except for those in the 12-14 age group. We also calculated the T3/T4 and rT3/T4 ratios to elucidate the reason for the higher rT3 in patients with DS; however, no useful findings were obtained. Thus, further investigation is needed to clarify our findings.

Chromosomal microarray and whole exome sequencing identify genetic causes of congenital hypothyroidism with extra-thyroidal congenital malformations

BACKGROUND

Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder. Although most patients present with isolated CH, some patients present with CH and extra-thyroidal congenital malformations (ECMs), for which less is known about the underlying genetics. The aim of this study was to investigate the genetic mechanisms in patients with CH and ECMs using chromosomal microarray (CMA) and whole exome sequencing (WES).

METHODS

Peripheral venous blood samples were collected from 16 patients with CH and ECMs. Genomic DNA was extracted from peripheral blood leukocytes. CMA and WES were performed to detect copy number and single nucleotide variants.

RESULTS

CMA identified clinically significant copy number variants in 7 patients consistent with their phenotypes. For 6 of them, the genotype and phenotype suggested a syndromic diagnosis, and the remaining patient carried a pathogenic microdeletion and microduplication including GLIS3. WES analysis identified 9 different variants in 7 additional patients. The variants included 2 known mutations (c.1096C>T (p.Arg366Trp) in KCNQ1 and c.848C>A (p.Pro283Gln) in NKX2-5) and 7 novel variants: one nonsense mutation (c.4330C>T (p.Arg1444*) in ASXL3), one frameshift mutation (c.1253_1259delACTCTGG (p.Asp418fs) in TG), three missense variants (c.1472C>T (p.Thr491Ile) in TG, c.4604A>G (p.Asp1535Gly) in TG, and c.2139G>T (p.Glu713Asp) in DUOX2, and two splice site variants (c.944-1G>C and c.3693 + 1G>T) in DUOX2.

CONCLUSIONS

We report the first genetic study of CH patients with ECMs using CMA and WES. Overall, our detection rate for pathogenic and possibly pathogenic variants was 87.5% (14/16). We report 7 novel variants, expanding the mutational spectrum of TG, DUOX2, and ASXL3.

Thyroid Disorders in Subjects with Down Syndrome: An Update

Down syndrome (DS) is the commonest chromosomal disorder among live born infants. DS is associated with increased risk of endocrine abnormalities particularly thyroid gland disorders. The spectrum of thyroid dysfunction in patients with DS include congenital hypothyroidism, subclinical hypothyroidism, acquired hypothyroidism (autoimmune - non autoimmune), and hyperthyroidism. This review will focus on the characteristics of the different presentations of thyroid abnormalities in DS, screening and management recommendations. (www.actabiomedica.it)

Endocrine manifestations of Down syndrome

PURPOSE OF REVIEW

To summarize the recent developments in endocrine disorders associated with Down syndrome.

RECENT FINDINGS

Current research regarding bone health and Down syndrome continues to show an increased prevalence of low bone mass and highlights the importance of considering short stature when interpreting dual energy x-ray absorptiometry. The underlying cause of low bone density is an area of active research and will shape treatment and preventive measures. Risk of thyroid disease is present throughout the life course in individuals with Down syndrome. New approaches and understanding of the pathophysiology and management of subclinical hypothyroidism continue to be explored. Individuals with Down syndrome are also at risk for other autoimmune conditions, with recent research revealing the role of the increased expression of the Autoimmune Regulatory gene on 21st chromosome. Lastly, Down-syndrome-specific growth charts were recently published and provide a better assessment of growth.

SUMMARY

Recent research confirms and expands on the previously known endocrinopathies in Down syndrome and provides more insight into potential underlying mechanisms.

Pattern of Thyroid Disorders in Children and Adolescents Seen at the Lagos University Teaching Hospital, Nigeria, Over a 10-year Period

Introduction:

Thyroid disorders account for a large proportion of pediatric endocrine disorders. Untreated hypothyroidism in childhood has permanent adverse effects on physical, intellectual, and neurological development. However, few studies have reported the pattern of pediatric thyroid disorders in Nigeria.

Objectives:

The objective of this study was to document the pattern of thyroid disorders in children and adolescents seen at the Lagos University Teaching Hospital (LUTH) over a 10-year period.

Participants and Methods:

This is a retrospective descriptive study involving children with thyroid disorders seen from January 1, 2006 to December 31, 2015.

Results:

Seventy-one patients with thyroid disorders (0.13%) were seen out of 52,800 new cases (incidence of 1/1000 new cases) comprising 13.4% of 546 pediatric endocrine cases with a male:female ratio of 1:1.2. Median (range) age at presentation was 1.6 (0.001–14) years. Congenital hypothyroidism (CH) constituted a major proportion of cases (46.7%), with a median (range) age at presentation of 9 (1.5–24) months. Down syndrome constituted 45% of patients with CH with associated congenital heart defects in eight (53%) patients. Acquired hypothyroidism was seen in ten patients (five goitrous and five nongoitrous). Six patients had hypothyroidism associated with multiple anterior pituitary hormone deficiency. Nine patients (all females) had hyperthyroidism with confirmed Graves' disease in 5 (55.6%), with mean age at presentation being 9.4 ± 2.09 years. Other conditions were euthyroid sick syndrome (2.8%), euthyroid goiter (1.4%), and acute thyroiditis (1.4%). Eight infants of mothers on treatment for hyperthyroidism ( first seen between the 7^th h of life to 2 months of age) had transient hypothyroidism while one 8-day-old had transient hyperthyroidism.

Conclusion:

CH was the most common disorder encountered with late age at presentation. Routine newborn screening and maintaining a high index of suspicion are advocated.