Basan Syndrome

At a glance

Ectodermal dysplasia, absent dermatoglyphic pattern, changes in nails, simian crease, and abnormal sweating.

Incidence

Unknown. In 1964, Henry W. Baird described 13 individuals without dermal ridges in three generations of one family, but the disorder is named after M. Basan who in 1965 described affected persons of both genders in three generations of one family. Since then, a limited number of articles describing various patients with features of the syndrome have been published. However, a clear distinction between epidermal ridge disorders remains difficult due to the heterogeneous nature of these conditions and the lack of an accepted classification system.

Genetic inheritance

Autosomal dominant inheritance. Genetic heterogeneity results in a spectrum of familial absence/dissociation of dermal ridge patterns. The defect has been mapped to chromosome 4q22.3 and affects the SMARCAD1 gene (SWI/SNF [SWItch/Sucrose Non-Fermentable]-related, matrix-associated actin-dependent regulator of chromatin, subfamily A, containing DEAD/H box 1). This gene encodes for two protein isoforms of different lengths and sites of transcription initiation. The long (major) isoform is expressed ubiquitously, while the short isoform is almost exclusively found in skin fibroblasts and (to a lesser extent) in keratinocytes suggesting a pivotal role for the SMARCAD1-skin specific (short) isoform in the dermatoglyph formation and sweat gland development. SMARCAD1-proteins also play a critical role in chromatin remodeling and particularly in assisting in the repair of DNA double-strand breaks.

Diagnosis

Based on the clinical examination, family history, and genetic analysis.

Clinical aspects

The ectodermal dysplasia presents with a lack (or anomalies) of dermal ridge patterns and sweat glands on palms and soles. Over time, the palmar and plantar skin becomes thickened, calloused and hard, and painful fissures and blisters may develop when exposed to hot or cold temperatures. The fingertips are tapered and cold sensitivity on hands and feet is increased. Clinodactyly of the fifth finger, simian crease and cutaneous syndactyly or webbing of toes have occasionally been described. Flexion and contractures of the fingers and toes are occasionally present. The nails are rough, with transverse groves and longitudinal ridges. The syndrome is further characterized by multiple congenital, but transient milia (keratin-filled cysts 1-2 mm in diameter, also known as “milk spots”) mainly found on the chin (but may extend to scalp, forehead, cheeks and nose) that disappear within the first 6 months of life. Neonatal vesicular/bullous lesions on the fingers and soles typically resolve in the first month of life. The skin appears smooth with a leather-like texture. No other congenital abnormalities are associated with the condition. Life expectancy appears to be normal.

Precautions before anesthesia

Premedication with anticholinergic agents (eg, atropine) should be avoided in neonates and infants due to the reduced number of sweat glands, potentially resulting in hyperthermia, and abnormal body temperature ...