ALTERNATE NAMES

Au-Kline-Okamoto Syndrome; HNRNPK-Related Neurodevelopmental Disorder; Okamoto Syndrome

DESCRIPTION

Au-Kline syndrome is a condition that affects many body systems. It is caused by mutations in the HNRNPK gene. Children with this condition typically have weak muscle tone (hypotonia), intellectual disability, delayed development, and delayed speech with some children able to say only one or a few words or are never able to speak at all. Some children with Au-Kline syndrome have an abnormal curvature of the spine (scoliosis). In addition, affected children learn to walk later than usual, and some are never able to walk on their own.

Malformations of the heart, blood vessels, kidneys, or bones can also occur in children with Au-Kline syndrome. In some affected individuals, the large blood vessel that distributes blood from the heart to the rest of the body (the aorta) becomes weakened and stretched (aortic dilatation), which can be life-threatening.

Au-Kline syndrome can sometimes affect the autonomic nervous system, which controls involuntary body functions, such as digestion and regulation of body temperature. In people with Au-Kline syndrome, abnormalities in this system can lead to digestive problems, difficulty feeling pain, abnormal sweating, and an inability to adjust to high heat.

Additional complications can include craniosynostosis, feeding difficulty, vision issues, osteopenia (reduced bone density), and other skeletal anomalies.

DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM CODING

Diagnostic testing: The diagnosis of Au-Kline syndrome is based on:

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  Symptoms;

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  Clinical examination; and

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  Genetic testing for mutations in the HNRNPK gene.

Physical findings: Signs and symptoms of Au-Kline syndrome may include:

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  Hypotonia (muscle weakness);

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  Developmental delay/intellectual disability;

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  Central nervous system malformations;

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  Vision issues;

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  Hyporeflexia or areflexia (decreased or absent muscle reflex response);

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  High pain tolerance;

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  Dysmorphic facies (abnormal differences in facial structure);

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  Craniosynostosis (fusion of bones in an infant’s skull);

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  Cleft palate;

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  Congenital heart defects;

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  Cryptorchidism (undescended testicles);

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  Hydronephrosis (built up urine in the kidneys);

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  Feeding difficulties;

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  Digestive problems;

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  Inability to regulate body heat;

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  Muscle weakness;

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  Growth deficiency;

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  Scoliosis;

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  Osteopenia (reduced bone density); and

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  Hearing loss.

ICD-9: 759.9

ICD-10: Q87.8

PROGRESSION

The symptoms of Au-Kline syndrome may start to appear as a newborn and as an infant. Other symptoms may begin in a single age range, or during several age ranges. The severity of features can vary greatly between individuals, and some may experience complications related to heart, kidney, or skeletal abnormalities that may require ongoing medical management throughout their lives.

TREATMENT

Currently, there is no cure for Au-Kline syndrome. Treatment focuses on supportive care to improve quality of life, maximize function, and reduce complications.

Physical therapy may be helpful for hypotonia (muscle weakness). Feeding therapy for poor weight gain; gastrostomy tube placement may be required for persistent feeding issues.

Individuals with autonomic dysfunction may see a neurologist. Bisphosphonate treatment could be considered for those with osteopenia (low bone mass) who experience recurrent fractures. Standard treatments for other symptoms of Au-Kline syndrome may occur.

Suggested MER for Evaluation:

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  Clinical history and physical examination that describes the diagnostic features of the impairment; and

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  Genetic sequencing tests confirming mutation of the HNRNPK gene.

Suggested Listings for Evaluation:

Meets

102.00

104.00

105.00

112.00

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