In a new case report titled “A rare case of hereditary sensory and autonomic neuropathy type II” published in the Clinical Case Reports (Wiley) journal, a team of doctors led by Dr. Yethindra Vityala from Hyderabad, Telangana, reported a very rare case of a 29-year-old man diagnosed with hereditary sensory and autonomic neuropathy (HSAN) type II, including the various complications that have presented since his childhood.
Hereditary sensory and autonomic neuropathy (HSAN) is a clinically and genetically uncommon category of inherited peripheral nerve disorders that primarily affect sensory and autonomic neurons. HSAN is classified into categories I to V based on the inheritance pattern, onset age, and predominant clinical symptoms. The classification of HSANs is complicated and not always agreed upon by experts. In addition, HSANs are broadly categorized as peripheral neuropathies or disorders of the peripheral nervous system, which includes all nerves outside the central nervous system (i.e., the brain and spinal cord). With the discovery of several new causal genes, however, this classification has been expanded to HSAN types 1–8. Others are related to or identical to familial dysautonomia (Riley-Day syndrome). It can begin at birth and frequently occurs before puberty.
HSAN type II (HSAN2) is an autosomal recessive axonal sensory neuropathy with an early onset. It is characteriSed by progressive distal sensory loss affecting all modalities, which typically results in severe complications including recurrent ulcerations, soft tissue infections, and osteomyelitis, which may necessitate amputation of the distal extremities. Likewise, skin trophic changes are common. Symptoms such as anhidrosis, apnea, blood pressure fluctuations, and gastro-intestinal disturbances may be present due to autonomic dysfunction, but they are typically not prominent. Although motor involvement is uncommon, it is possible and is typically much less severe than sensory disturbance. It is typically an autosomal recessive disorder caused by mutations in the HSN2 exons of the WNK1, FAM134B, and KIF1A genes on chromosome 12p13.33, resulting in diminished pain,
temperture, and contact sensations, as well as ulcers, burns, auto-amputations, and impaired wound repair.
The patient was born with strabismus. Right ankle septic arthritis manifested in him at the age of eight. At the age of 14, he developed right knee prepatellar septic bursitis, which was treated surgically. He developed osteomyelitis of the patella postoperatively, for which extraarticular knee resection was conducted; arthrodesis of the knee joint using an external fixation device was ineffective. Due to the osteomyelitis-related surgeries, the patient’s right lower limb was abbreviated by 10 centimeters, and he required crutches and shoes with a 15-centimeter platform, rendering him incapacitated.
Due to his incessant gnawing, he developed numerous skin ulcers, lost teeth, and had his tongue split in two. On both hands and feet, thickened palms, soles, and digits, as well as nail deformities, were observed. Observations included the unilateral absence of a deep tendon reflex, decreased heat sensitivity, absence of bodywide pain sensation, hyporeflexia, dysphagia with preserved gag and palatal reflexes, normal cardiovascular reflexes, and casual perspiration. In addition to producing normal results, magnetic resonance imaging of the brain also revealed axonal sensory neuropathy.
Subsequently, the patient was referred for genetic testing. The presumptive diagnoses were Moebius syndrome or HSAN, based on the age of onset, the clinical symptoms, and the results of the electroencephalogram. A novel homozygous pathogenic mutation, c.1426del (p.Gln476Argfs*57), was identified in the FAM134B locus, and HSAN2 was definitively diagnosed.
This is the first known case of type II hereditary sensory and autonomic neuropathy in Central Asia.
If proper supportive care is not given to the patient, the outcome of this condition could be catastrophic.
The patient is monitored once per month in the outpatient department.
