Barber–Say Syndrome
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Barber-Say syndrome (BSS) is a very rare
congenital disorder A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities ca ...
associated with excessive hair growth (
hypertrichosis Hypertrichosis is an abnormal amount of hair growth over the body. The two distinct types of hypertrichosis are generalized hypertrichosis, which occurs over the entire body, and localized hypertrichosis, which is restricted to a certain area. ...
), fragile (
atrophic Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply t ...
) skin, eyelid deformities (
ectropion Ectropion is a medical condition in which the lower eyelid turns outwards. It is one of the notable aspects of newborns exhibiting congenital Harlequin-type ichthyosis, but ectropion can occur due to any weakening of tissue of the lower eyelid ...
), and an overly broad mouth ( macrostomia). Barber-Say syndrome is phenotypically similar to
Ablepharon macrostomia syndrome Ablepharon macrostomia syndrome (AMS) is an extremely rare, autosomal dominant genetic disorder characterized by abnormal Phenotype, phenotypic appearances that primarily affect the head and face as well as the skull, skin, fingers and genitals. A ...
, which is also associated with dominant mutations in ''TWIST2''.


Signs and symptoms

* Severe hypertrichosis, especially of the back * Skin abnormalities, including hyperlaxity and redundancy * Facial dysmorphism, including macrostomia * Eyelid deformities, in * Abnormal and low-set ears * Bulbous nasal tip with hypoplastic alae nasi * Low frontal hairline


Genetics

Multiple cases of parent-to-child transmission suggest that Barber-Say syndrome exhibits autosomal dominant inheritance. Exome sequencing and expression studies have shown that BSS is caused by mutations in the ''
TWIST2 Twist-related protein 2 is a protein that in humans is encoded by the ''TWIST2'' gene. The protein encoded by this gene is a basic helix-loop-helix (bHLH) transcription factor and shares similarity with another bHLH transcription factor, TWIST1. ...
'' gene that affect a highly conserved residue of TWIST2 (twist-related protein 2). TWIST2 is a
basic helix-loop-helix BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
transcription factor that binds to E-box DNA motifs (5'-CANNTG-3') as a heterodimer and inhibits transcriptional activation. Because TWIST2 mediates mesenchymal stem cell differentiation and prevents premature or ectopic osteoblast differentiation, mutations in TWIST2 that disrupt these functions by altering DNA-binding activity could explain many of the phenotypes of BSS.


Diagnosis


Epidemiology

The prevalence of Barber Say syndrome is less than 1 in 1,000,000. As of 2017, only 15 cases have been reported in the literature.


References


External links

{{DEFAULTSORT:Barber-Say syndrome Autosomal dominant disorders Rare genetic syndromes Intersex variations