Hapnes Boman Skeie Syndrome - Causes, Clinical Features, Diagnosis, and Management

Introduction

Rare genetic disorders are genetic conditions that affect a small percentage of the population, often fewer than one in 2000 people. These disorders are usually caused by gene changes or mutations responsible for producing proteins essential for normal bodily functions. Rare genetic disorders may be inherited from parents or caused by spontaneous mutations during fetal development or later in life.

Many rare genetic disorders are poorly understood and can be challenging to diagnose. Symptoms and severity can vary widely between individuals, making it challenging for doctors to identify and treat those conditions.

What Is Hapnes Boman Skeie Syndrome?

Hapnes Boman Skeie syndrome is a rare congenital disorder characterized by the inability to extend the fingers that is caused due to the abnormal or uncommon attachment of the extensor tendons of the ring and little fingers (ulnar fingers) on both limbs. The other names for this syndrome include

• Anomalous insertion of the extensor tendons of the fingers.

• Tendons, extensor, of fingers, anomalous insertion of.

• Extensor tendons of finger anomalies.

This is an extremely rare condition, with an incidence of fewer than one in one million people. This syndrome was last reported in the literature in 1989, and no further descriptions have been made.

Hapnes Boman Skeie Syndrome Cases That Are Presented in Literature.

In 1980, Hapnes et al. reported this syndrome in a mother and daughter with the characteristic feature of bilateral abnormal attachment of the extensor tendons to the ulnar fingers. The normal positioning of the tendons should be on the dorsal side of the phalanges, but in these cases reported, they were attached to the medial and lateral sides of the phalanges. This resulted in a 70-degree flexion of the mid-phalangeal joints, leading to the inability to extend the fingers. It was reported that both patients got satisfactory function after reconstructive surgery.

What Causes Hapnes Boman Skeie Syndrome?

• This syndrome is present from birth and is believed to be caused by genetic causes like mutations.

• The exact cause and the exact genes involved in this condition are unknown.

• The mode of inheritance is proposed to be autosomal dominant. In an autosomal dominant inheritance pattern, the individual has one copy of the mutated gene and is affected by the disorder.

• The chances of the offspring of an affected individual getting the disease are 50 percent in an autosomal dominant inheritance pattern.

What Are the Clinical Features of Hapnes Boman Skeie Syndrome?

The symptoms of this syndrome start appearing as a newborn. The severity of the symptoms may vary between the different affected individuals. Some of the symptoms associated with the syndrome are listed below.

• Camptodactyly of the Finger - It is the most frequently occurring symptom. This is due to the bilateral attachment of the extensor tendons to the medial and lateral aspects of the phalanges (bones of the fingers). This abnormal attachment results in constant flexion in the mid-phalangeal joint, which leads to the inability to extend the fingers. Camptodactyly may cause pain, stiffness, weakness, and limited mobility of fingers in addition to the apparent finger posture or deformity.

• Multiple Lipomas - Lipomas are slow-growing, noncancerous fatty tumors between the skin and underlying muscle. Individuals affected by Hapnes Boman Skeie syndrome are reported to have multiple lipomas.

• Xanthomatosis - A condition in which there are multiple firm, yellowish, lipid-filled nodules (xanthomas) present in the skin is called xanthomatosis. This condition is a very frequent symptom of this syndrome.

• Osteoporosis - A bone disease in which the bones become weak and porous with low bone mass. Osteoporosis is a less frequent symptom.

• Limited Joint Mobility - One or more joints have limited mobility in individuals affected by Hapnes Boman Skeie syndrome. This is also a less frequent symptom that is associated with this condition.

• Skeletal Muscle Atrophy - This also occurs less frequently and is characterized by reduced muscle mass.

How Is Hapnes Boman Skeie Syndrome Diagnosed?

• The diagnosis is made using a combination of clinical evaluation, medical history, imaging tests, and if necessary genetic tests.

• During clinical examination, the doctor checks for clinical signs and symptoms. The fingers are also assessed for deformities and abnormal postures.

• A complete medical and family history may be made to know about other family members with similar conditions and to eliminate other non-genetic causes of the disorder.

• X-rays and other imaging studies are done to evaluate the deformity's extent and help confirm the diagnosis.

• In some cases, additional testing may be required to rule out other underlying medical conditions that can cause similar symptoms.

• Genetic tests are done to confirm the diagnosis.

• Genetic counseling can be given to individuals and their family members to know about the disease and its risk of inheritance in future generations.

How Is Hapnes Boman Skeie Syndrome Managed?

There is no specific treatment plan or cure for Hapnes Boman Skeie syndrome. Treatment of this syndrome is aimed at reducing the symptoms caused due to various clinical conditions associated. Some of the treatment options are listed below.

• Observation - Cases with mild symptoms are monitored regularly and may not require immediate treatment.

• Physical Therapy - Physical therapy for the affected hand is done to help with the range of motion, strength, and flexibility. Other joints with limited mobility are also treated using physical therapy.

• Medications and Injections - Pain medications are prescribed if the patient presents with pain. Other injections and medications like corticosteroids are given to reduce inflammations due to the xanthomas.

• Treatment of Other Associated Conditions - Xanthomas may be associated with underlying metabolic disorders. This should be treated using appropriate drugs. Other associated signs and symptoms are treated if necessary and severe.

• Surgery - The camptodactyly and abnormal attachment of the extensor tendons are corrected using reconstructive surgery that may involve releasing or repositioning the tendons to their correct location, repairing damaged ligaments, or fusing the affected joint. Larger lipomas and xanthomas may also be removed surgically.

• Lifestyle Modifications - Lifestyle modifications like regular exercise and a healthy diet may help improve the symptoms and prevent complications.

Conclusion

There needs to be more information available about the Hapnes Boman Skeie syndrome in literature, and only a few cases have been reported. This makes it difficult to understand and diagnose the syndrome better. More research about the syndrome and its genetic relevance may help in better understanding this syndrome.