Johanson-Blizzard Syndrome - Causes and Treatment Options

Introduction:

Johanson-Blizzard syndrome is a rare genetic disorder that affects many organs of the body. It was first described by Johanson and Blizzard in 1971, and the defective gene was identified in 2006 by Zenker et al. The signs and symptoms and the severity of Johanson-Blizzard syndrome vary among affected individuals. However, the characteristic features of Johanson-Blizzard syndrome include pancreatic insufficiency (abnormal development of pancreas) causing malabsorption, failure to thrive and grow at the expected rate during the first years of life causing short stature, abnormalities of permanent teeth, abnormalities of the skull and facial region such as small beak-shaped nose, and intellectual disability. Most of the symptoms are present since birth (congenital) or early childhood. This syndrome is believed to be caused by changes in the UBR1 gene. Johanson-Blizzard syndrome affects males and females in equal numbers. As it is a rare disorder, the incidence is estimated to be one in 250000 births.

What Are the Signs and Symptoms of Johanson-Blizzard Syndrome?

The specific signs and symptoms found in almost all the patients of Johanson-Blizzard syndrome are:

• Pancreatic insufficiency.

• Abnormalities of the tooth.

• A characteristic shape of the nose.

Other signs and symptoms in infants include the following:

• Unusually small nose appearing beak-shaped due to absence of or under development of nasal wings.

• Underdeveloped small upper jaw.

• A small pointed chin.

• Narrow long upper lip.

• The circumference of a child’s head is smaller than expected for that age and gender.

• Some of the affected children may not have small openings in the inner corners of the eyelids from where the tears drain normally or an abnormal passage that drains tears directly to the surface of the skin from the inner corner of the eyelids.

• Severe facial clefting, including cleft lip and palate and lateral facial clefts extending to the lower eyelid from the nasal region.

• Low birth weight with hypotonia (generalized poor muscle tone).

• Developmental delays and intellectual disability.

• Hearing loss or deafness.

• Growth deficiency due to malabsorption and pancreatic insufficiency.

• Tooth abnormalities like abnormally small, cone-shaped, widely spaced teeth with short, irregular, malformed roots. Most permanent teeth are absent in children.

• Affected individuals show abnormally decreased thyroid gland activity and hypothyroidism (underproduction of thyroid hormones).

• Abnormalities include the persistence of the anal membrane resulting in full or partial closure of the anus, preventing the normal passage of the bowel contents.

• In males, abnormal placement of the urinary opening on the underside of the penis can be seen.

• Small, underdeveloped nipples in infants and children.

• Abnormally high susceptibility to repeated infections.

• Congenital heart defects include a hole in the septum separating the upper or lower chambers of the heart.

• Deficiency of growth hormone.

• The juvenile onset of diabetes.

What Is the Cause of Johanson-Blizzard Syndrome?

Johanson-Blizzard syndrome is caused by changes in the UBR1 (ubiquitin E3 ligase) gene. It is an autosomal recessive syndrome. The UBR1 gene encodes a protein called the UBR1 protein. Changes in this gene cause deficient levels of functional UBR1 protein. This protein is necessary for various chemical processes in the body. It is usually found in high levels in the exocrine cells of the pancreas, but it is also found in other tissues as well. Deficient levels of this protein ultimately lead to the findings and physical features of Johanson-Blizzard syndrome. But how it happens is not known to the researchers.

How to Diagnose Johanson-Blizzard Syndrome?

The diagnosis of Johanson-Blizzard syndrome is made on the basis of the identification of the characteristic symptoms, patient history, and a thorough physical evaluation. The diagnosis of Johanson-Blizzard syndrome can be confirmed through molecular genetic testing that can identify the characteristic changes or mutations of the UBR1 gene that is responsible for causing this syndrome.

Other tests may be recommended to evaluate the severity of the Johanson-Blizzard syndrome. These tests include hearing tests to check the presence and degree of hearing loss or computed tomography (CT) scan that is helpful in determining the extent of fatty filtration of the pancreas. The affected infants and children should be screened for the development of complications such as hypopituitarism, congenital heart defects, hypothyroidism, and juvenile-onset diabetes.

What Are the Treatment Options for Johanson-Blizzard Syndrome?

• The treatment plan for Johanson-Blizzard syndrome is directed toward the specific symptoms that are specified in each individual. The treatment may need the coordinated efforts and comprehensive treatment plan of a team of specialists, including pediatricians, dental surgeons, surgeons, speech pathologists, endocrinologists, gastroenterologists, cardiologists, and other medical healthcare professionals.

• The treatment therapies for Johanson-Blizzard syndrome are supportive and symptomatic. Individuals who suffer from this syndrome generally require lifelong pancreatic enzyme supplements like oral pancreatin to promote adequate absorption of fats and other nutrients. In most cases, vitamin supplements are prescribed to prevent or treat vitamin deficiencies resulting from malabsorption due to pancreatic insufficiency.

• A special diet with high protein supplements that can be easily absorbed is also prescribed to make sure that an affected individual’s nutritional demands are met.

• People with hypothyroidism need immediate thyroxine hormone replacement therapy. Especially in infants, it is mandatory that hypothyroidism be diagnosed early and managed immediately.

• Other abnormalities associated with Johanson-Blizzard syndrome can be corrected surgically. These include certain craniofacial, cardiac, genitourinary, and other malformations associated with this syndrome. Depending on the severity of the anal abnormalities, surgery may be performed to correct or reconstruct the anus or create an opening between the large intestine and the surface of the body to allow passage of bowel contents. The surgical procedure will depend on the anatomical abnormalities' severity and location and associated symptoms.

• The dental abnormalities associated with Johanson-Blizzard syndrome can be treated through bonding agents, dentures, and other supportive techniques.

• Hearing loss is treated with hearing aids.

Conclusion:

Johanson-Blizzard syndrome is a rare, inherited disorder that affects many organ systems with a wide range of congenital abnormalities. The spectrum of potential physical findings and features associated with Johanson-Blizzard syndrome is varied and wide and differs dramatically from person to person. Early intervention is necessary to ensure children with Johanson-Blizzard syndrome reach their potential. Genetic counseling has proven to be beneficial for affected individuals and their families.