Thyroid Disorders with Cutaneous Manifestations (eBook)

Anatomy and Embryology of the Thyroid Gland.- Hormones.- Classification and Epidemiology of Thyroid Disease.- Laboratory Diagnosis of Thyroid Disease.- Thyroglossal Duct Cysts.- Thyroid Cancer and the Skin.- Chromosomes, Genes, and the Thyroid Gland.- Cutaneous Manifestations of Hyperthyroidism.- Cutaneous Manifestations of Hypothyroidism.- Pretibial Myxedema (Thyroid Dermopathy).- Alopecia and Thyroid Disease.- Chronic Idiopathic Urticaria and Thyroid Disease.- Dermatologic Disorders Associated with Thyroid Disease.- Potential Therapeutic Uses of Thyroid Hormone.

"7 Chromosomes, Genes, and the Thyroid Gland (p. 55-56)

Analisa V. Halpern and Rhonda E. Schnur

Editorial Perspective

As molecular genetics advances at breakneck speed, unraveling genetic mysteries via genomics, proteomics, and microarray analysis, we are at the cusp of the era of “personalized” medicine, by which knowledge of our unique genetic blueprint will allow us to anticipate, and hopefully obviate, a host of heritable diseases.

The genetic aspects of thyroid diseases are manifest in all age groups, from the neonate with congenital hypothyroidism due to a newly defined mutation in thyroid hormonogenesis, to the adult who is genetically predisposed to autoimmune thyroid disease because of aberrations of autoregulatory genes. The recognition of thyroid disease is of paramount importance, especially in the neonatal period. A failure to diagnose these diseases will have a profoundly adverse effect on the growth and development of the child. It is essential that practitioners are cognizant of how common thyroid diseases are in patients with certain genetic syndromes. Addressing these issues is essential for proper care.

I recall seeing a patient with Down syndrome who was frequently treated for repeated bouts of secondarily infected nummular eczema. Recognizing that approximately one-third of patients with Down syndrome have thyroid disorders, a thyroid-stimulating hormone (TSH) level was checked. The patient was found to be hypothyroid; once she was placed on thyroid hormone, the xerotic skin that predisposed her to developing eczema resolved, and secondary infection was no longer an issue.

This chapter offers current insights into the pathogenesis and dermatologic features of a host of chromosomal, mosaic, and inborn errors of metabolism that also affect the thyroid gland. When confronted with syndromal patients, thoughtful clinicians will entertain the possibility that there may be coexistent thyroid gland disorders and will research this by utilizing resources such as OMIM (the Online Mendelian Inheritance of Man database). It is a worthwhile endeavor to do so as maintaining a euthyroid state is crucial for optimal health.

Introduction

This chapter focuses on selected disorders caused by chromosome or single-gene changes that affect thyroid function. Most are detectable in the infant or young child but continue to have an impact on health throughout life. The elucidation of specific transcription factors that affect thyroid organogenesis and the biochemical pathways leading to thyroid hormone production and regulation within the thyroid gland are also contributing to a better understanding of mechanisms leading to congenital hypothyroidism (CH).

Common chromosomal disorders and microdeletion syndromes that are associated with thyroid dysfunction are reviewed. Advances in the ability to detect subtle chromosome dosage abnormalities using the techniques of comparative genomic hybridization or microarray analysis (CGH/CMA) are likely to lead to the recognition of new genetic mechanisms for thyroid organogenesis and hormonal regulation."