Bamforth syndrome

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.

Orpha Number: 1226

Definition

A very rare syndrome of congenital hypothyroidism characterized by thyroid dysgenesis (in most cases athyreosis), cleft palate and spiky hair, with or without choanal atresia, and bifid epiglottis. Facial dysmorphism and porencephaly have been reported in isolated cases.

Epidemiology

Only 8 patients from 6 families have been reported to date.

Clinical description

The syndrome is typically observed at birth with cleft palate, spiky hair and thyroid dysgenesis (in most cases athyreosis) leading to congenital hypothyroidism that manifests with lethargy, poor feeding, macroglossia, cold or mottled skin, persistent jaundice, and umbilical hernia. Neonatal hyperbilirubinemia is also common. Some may also present with choanal atresia and bifid epiglottis. Facial dysmorphism, consisting of microcephaly, hypertelorism, anteverted nares, narrow nasal bridge, low-set ears, small jaw and retrognathia, has been reported in one case. Porencephaly was also recently described in one case.

Etiology

Bamforth-Lazarus syndrome is due to homozygous loss-of-function missense mutations located within the forkhead domain of the FOXE1 gene (9q22), encoding thyroid transcription factor 2 (TTF-2). TTF-2 is expressed in the thyroid gland (as well as elsewhere like the tongue, epiglottis and palate) and is thought to play a crucial role in thyroid morphogenesis. Cases reported so far have all been due to homozygous loss-of-function mutations apart from one case described with a novel FOXE1 homozygous mutation causing increased thyroid gene expression.

Diagnostic methods

Diagnosis is based on clinical findings of congenital hypothyroidism with cleft palate and spiky hair along with findings of thyroid ultrasonography (USG) and computed tomography examination. Thyroid tissue is either completely absent or non-functional. Serum thyroid stimulation hormone (TSH) levels should be measured (levels will be elevated on newborn screening filter paper test, as is seen in all cases of athyreosis) to determine necessary treatment dosage. Molecular genetic testing can identify a mutation in the FOXE1 gene, confirming diagnosis.

Differential diagnosis

Differential diagnoses include other forms of syndromic hypothyroidism such as Johanson-Blizzard syndrome.

Antenatal diagnosis

Whilst prenatal diagnosis is not performed, a cleft palate and, in some cases, polyhydramnios (resulting from choanal atresia) may be observed during routine antenatal sonography.

Genetic counseling

The disease is inherited autosomal recessively and genetic counseling is possible. Most of the patients reported to date came from consanguineous parents, both being heterozygous for the genetic mutation. Where both parents are heterozygous carriers, there is 25% risk of transmitting the disease to offspring.

Management and treatment

Thyroid hormone replacement therapy is the standard treatment for those with Bamforth-Lazarus syndrome and should be started as soon as possible. The dosage of synthetic thyroxine (T4) necessary depends on the patient's age, weight and any other medical conditions. Regular follow up is recommended to monitor any fluctuation in TSH levels and treatment is lifelong. In neonates born with hyperbilirubinemia, phototherapy is often effective. Surgical procedures for cleft palate (maxillo-facial reconstruction and plastic surgery) and choanal atresia (surgery to reopen the nasal passages) should be discussed in a specialized health center. Speech therapy may also be required.

Prognosis

With proper treatment adherence the prognosis is good and children can have normal physical growth, pubertal development, and anterior pituitary function. Quality of life, however, can be affected by cleft palate/choanal atresia as multiple surgeries may be necessary. Intellectual development is normal if treatment for hypothyroidism is not delayed.

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