Johanson Blizzard syndrome
Overview
A rare genetic disorder involving a range of abnormalities including a characteristic beak-like small nose, hypothyroidism and deafness.
Symptoms
* Fetal growth retardation * Intellectual impairment * Sensorineural deafness * Reduced muscle tone * Microcephaly mild to moderate * Midline scalp defect * Variable sparse hair * Frontal upswept hair * Hypoplastic nostrils * Aplastic nostrils * Nasolacrimal duct cutaneous fistulae * Hypoplastic deciduous teeth * Absent permanent teeth * Imperforate anus * Anteriorly placed anus * Recto-ureteral fistula * Rectovaginal fistula * Caliectasis to hydronephrosis * Genitourinary defects * Septate vagina * Double vagina * Undescended testes * Small penis * Hypospadias * Single urogenital orifice * Hypothyroidism * Pancreatic insufficiency * Malabsorption
Causes
In infants, cretinism usually results from defective embryonic development that causes congenital absence or underdevelopment of the thyroid gland. The next most common cause can be traced to an inherited enzymatic defect in the synthesis of thyroxine (T4) caused by an autosomal recessive gene. Less frequently, antithyroid drugs taken during pregnancy produce cretinism in infants. In children older than age 2, cretinism usually results from chronic autoimmune thyroiditis.
Treatment
Early detection is mandatory to prevent irreversible mental retardation and permit normal physical development. Treatment of infants younger than age 1 consists of replacement therapy with oral levothyroxine, beginning with moderate doses. Dosage gradually increases to levels sufficient for lifelong maintenance. (Rapid increase in dosage may precipitate thyrotoxicity.) Doses are proportionately higher in children than in adults because children metabolize thyroid hormone more quickly. Therapy in older