Bjornstad syndrome is a rare autosomal recessive genetic disorder characterized by brittle and fragile short hair (known as pili torti) and hearing loss that appear in the first several years of life. The disease stems from mutations in the BCS1L proteins that are responsible for mitochondrial function. Additional findings are hypogonadism and mental retardation. The diagnosis can be made based on clinical findings, a positive family history, and genetic studies that confirm the specific mutation.
Initially described 50 years ago, Bjornstad syndrome (BS) is a rare genetic disorder that arises due to mutations in BCS1L proteins that play an essential role in mitochondrial function [1] [2] [3] [4]. The location of genes that code for these proteins was subsequently identified on chromosome 2 and an autosomal recessive pattern of inheritance was established [1] [2] [3]. Very few cases of BS have been described in the literature. The clinical presentation is centered around two components - pili torti and hearing loss [3] [5] [6]. Pili torti (denoting the twisting of hair around their axis) is a term used to illustrate the appearance of short and brittle hair (without any pigment) that occurs as a result of the previously mentioned mutations, consequently leading to hair loss in the first few years of life [1] [5] [6]. For some reason, the hair on the head is principally affected, whereas the other parts of the body (including the face) are spared. Conversely, hearing loss is congenital in nature and develops by three years in the majority of cases [1] [5]. The severity of hearing impairment may be mild, moderate, or severe enough to lead to deafness [1] [3]. Isolated studies have reported mental retardation and hypogonadism as additional signs of BS [5].
Given the rare occurrence of Bjornstad syndrome in clinical practice (approximately 20 cases have been described by the end of the 20th century) [2], the diagnosis may be difficult to attain. For this reason, the physician must obtain a detailed patient history and perform a meticulous physical examination that will provide the opportunity to identify the hallmarks of BS. The onset of deafness and hair loss must be assessed with the parents of the affected child, as most cases are described in infancy or early childhood. In addition, a complete family history that covers the presence of similar findings in siblings or parents might be of great benefit for raising clinical suspicion toward a familial disorder. Auditory testing should be conducted in order to determine the extent of hearing loss, whereas microscopic examination of the hair will reveal typical twists of the hair shaft that must point to BS [4] [7]. Transmission electron microscopy (TEM) has been used (where possible) as a method to confirm pili torti [4] [6]. To confirm the diagnosis, however, genetic testing to detect BCS1L mutations is a mandatory procedure.