Thyroid Hypoplasia as a Cause of Congenital Hypothyroidism in Monozygotic Twins Concordant for Rubinstein-Taybi Syndrome

Mustafa Ali Akın,Aslıhan Kiraz,Leyla Akın,Tamer Güneş,Sena Kara Oncu,Dilek Çoban,Selim Kurtoğlu

doi:10.4274/jcrpe.v3i1.07

Mustafa Ali Akın, Aslıhan Kiraz + Show 5 more

Open Access

https://doi.org/10.4274/jcrpe.v3i1.07

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Abstract

Rubinstein-Taybi syndrome (RSTS), a genetic disorder characterized by growth retardation, mental deficiency, dysmorphic face, broad thumbs and large toes, generally affects monozygotic twins concordantly. Thyroid hypoplasia (TH) is a common cause of congenital hypothyroidism (CH) and often accompanies dysmorphic syndromes. A pair of female twins were admitted to our neonatology unit 16 hours after delivery. They were born at 35 weeks of gestation. Both twins had an unusual dysmorphic facial appearance with microcephaly, as well as broad short thumbs and large toes. Based on the presence of characteristic dysmorphic features, the twins were diagnosed as RSTS. Thyroid function tests in the first twin revealed the following results: free thyroxine (T4) 8.4 pg/mL, thyrotropin (TSH) 4.62 mIU/L, thyroglobulin (TG) 213.24 ng/mL and a normal level of urinary iodine excretion (UIE). Thyroid function test results in the second twin in the second week were: free T4 5.9 pg/mL, TSH 9.02 mIU/L, TG 204.87 ng/mL, and normal UIE levels. Thyroid volumes were 0.36 mL and 0.31 mL in the first and second twin, respectively. TH was confirmed by technetium 99 m pertechnetate thyroid scans in both infants. Thyroid function tests normalized with L-thyroxine replacement therapy (10 μg/kg/day) around the end of the 3rd week of life. The infants were discharged planning their follow-up by both endocrinology and cardiology units. The rarity of cases of twins with RSTS (concordant) co-existing with CH led us to present this report. Conflict of interest:None declared.

Highlights

Rubinstein-Taybi syndrome (RSTS, OMIM 180849) is a rare condition, inherited in an autosomal dominant fashion and characterized by short stature, well-established craniofacial features, moderate to severe motor and intellectual disability, broad, often angulated thumbs, and enlarged first toes
Two cases of thyroid hypoplasia (TH) or Thyroid dysgenesis (TD) as the cause of congenital hypothyroidism (CH) in monozygotic twin sisters concordant for RSTS will be presented in this report
RSTS is a prototype of diseases with genetic heterogeneity

Summary

Introduction

Rubinstein-Taybi syndrome (RSTS, OMIM 180849) is a rare condition, inherited in an autosomal dominant fashion and characterized by short stature, well-established craniofacial features, moderate to severe motor and intellectual disability, broad, often angulated thumbs, and enlarged first toes. Various endocrinological problems are expected in patients with mutations of CREBBP since they disrupt the hormonal Ak›n MA et al Congenital Hypothyroidism in Twins with RSTS The only endocrinologic problem reported so far in patients with RSTS in neonatal period is CH without any abnormality in thyroid structure [10].

Results

Conclusion