TWIST2

Barber-Say Syndrome

Clinical Characteristics
Ocular Features: 

The ocular features consist mainly of skin changes in the lids including hyperlaxity and redundancy.  There may be ectropion of the lower eyelids and sparsity of the eyebrows.  Some evidence of micro- or ablepharon is often present.  Hypertelorism and exophthalmia have been described.

Systemic Features: 

Multiple external congenital anomalies are present at birth including skin laxity, hypertrichosis (especially of the forehead, neck and back), and low-set and malformed pinnae.  Macrostomia and thin lips with redundant facial skin are often evident.  The nose appears bulbous.  The thoracic skin can be atrophic and the nipples may be hypoplastic.  Hypospadias has been reported.  A highly arched or cleft palate may be present and some individuals have a conductive hearing loss.  The teeth are small and eruption may be delayed.  Cognitive deficits may be present and mental retardation has been reported. 

Genetics

Based on genotyping and the limited number of reported pedigrees, inheritance most likely follows an autosomal dominant pattern.  Direct parent to child transmission has been reported.  Detailed examination of parents sometimes reveals mild features that are easily missed.  Mutations in the TWIST2 gene have been found in 10 unrelated individuals with Barber-Say syndrome.

TWIST2 mutations have also been found in Setleis syndrome (227260) and in ablepharon-macrostomia syndrome (200110).  These conditions have some clinical features in common with Barber-Say syndrome.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

There is no known treatment for this disorder but correction of selected anomalies such as ectropion and cleft palate may be indicated.

References
Article Title: 

Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes

Marchegiani S, Davis T, Tessadori F, van Haaften G, Brancati F, Hoischen A, Huang H, Valkanas E, Pusey B, Schanze D, Venselaar H, Vulto-van Silfhout AT, Wolfe LA, Tifft CJ, Zerfas PM, Zambruno G, Kariminejad A, Sabbagh-Kermani F, Lee J, Tsokos MG, Lee CC, Ferraz V, da Silva EM, Stevens CA, Roche N, Bartsch O, Farndon P, Bermejo-Sanchez E, Brooks BP, Maduro V, Dallapiccola B, Ramos FJ, Chung HY, Le Caignec C, Martins F, Jacyk WK, Mazzanti L, Brunner HG, Bakkers J, Lin S, Malicdan MC, Boerkoel CF, Gahl WA, de Vries BB, van Haelst MM, Zenker M, Markello TC. Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes. Am J Hum Genet. 2015 Jul 2;97(1):99-110.

PubMed ID: 
26119818

Ablepharon-Macrostomia Syndrome

Clinical Characteristics
Ocular Features: 

The clinical features of this syndrome remain to be fully delineated.  Important ocular anomalies include malformations and sometimes absence of the upper and lower eyelids.  The eyelashes and eyebrows may be sparse or even missing.  The lid fissures, if present, may be shortened.  Deformities of the eyelids can lead to corneal exposure and secondary vision loss. 

Systemic Features: 

Other facial malformations include macrostomia which may be secondary to aberrant lip fusion.  Micrognathia has been described.  The external ears are often rudimentary, sometimes described as rosebuds.  The nasal bridge is low and the nostrils anteverted.  The zygomatic arches may be absent.  The nipples are often missing as well.  Scalp hair is sparse or even absent while the skin is dry, coarse, and often has redundant folds (cutis laxa).  Mild skin syndactyly, camptodactyly, finger contractures, and shortening of metacarpals have been noted.  The genitalia are often ambiguous and some patients have had ventral hernias.  Hearing loss can be a feature.  Growth retardation has been seen but developmental delays if present are mild.  Intelligence can be normal. 

Genetics

The majority of sibships suggest autosomal recessive inheritance although autosomal dominant inheritance has been proposed for several. One male child has been reported to have a partial deletion of chromosome 18 but other complex rearrangements were also present.

An amino acid substitution (lysine) in the basic domain of the TWIST2 gene has been found in seven families in which ablepharon-macrostomia followed an autosomal dominant pattern.  Mutations in the same TWIST2 domain but leading to substitutions of glutamine or alanine amino acids is responsible for the Barber-Say phenotype (209885).

Mutations in the TWIST2 gene may also be responsible for Setleis syndrome (227260). 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Cosmetic surgery can correct at least some of the malformations. Vigorous effort may be required to maintain corneal surface wetting. 

References
Article Title: 

Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes

Marchegiani S, Davis T, Tessadori F, van Haaften G, Brancati F, Hoischen A, Huang H, Valkanas E, Pusey B, Schanze D, Venselaar H, Vulto-van Silfhout AT, Wolfe LA, Tifft CJ, Zerfas PM, Zambruno G, Kariminejad A, Sabbagh-Kermani F, Lee J, Tsokos MG, Lee CC, Ferraz V, da Silva EM, Stevens CA, Roche N, Bartsch O, Farndon P, Bermejo-Sanchez E, Brooks BP, Maduro V, Dallapiccola B, Ramos FJ, Chung HY, Le Caignec C, Martins F, Jacyk WK, Mazzanti L, Brunner HG, Bakkers J, Lin S, Malicdan MC, Boerkoel CF, Gahl WA, de Vries BB, van Haelst MM, Zenker M, Markello TC. Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes. Am J Hum Genet. 2015 Jul 2;97(1):99-110.

PubMed ID: 
26119818

Setleis Syndrome

Clinical Characteristics
Ocular Features: 

The eyebrows slant upward and the lashes may be absent or appear in double rows as in distichiasis.  The periorbital skin can appear 'puckered with puffiness'.  The palpebral fissures appear short in some individuals.

Systemic Features: 

This condition is associated with a variety of facial skin anomalies.  The overall facial appearance has been described as 'leonine".  The facial skin often has some redundancy with a rubbery feel and may appear 'puffy' or wrinkled and puckered about the eyes. The lips are large.  The overall appearance has been described as 'leonine'. The nasal ridge can be flat and the nose can have a bulbous tip.  The teeth may be conical in shape.

Genetics

The genetic basis for this disorder seems to lie in heterozygous mutations in the TWIST2 gene (2q37.3).  Parent to child transmission has also been reported for some features but the signs in parents may be subtle.. 

The TWIST2 mutation was not present in several unrelated probands suggesting there is some genetic heterogeneity. Further, Brauer syndrome (136500) (focal facial dermal dysplasia or FFDD type I) is clinically somewhat similar to Setleis syndrome with respect to the distribution and nature of facial skin lesions and it has been suggested that the two disorders may be one and the same.  The gene responsible for Brauer syndrome has not been found but the condition is inherited in autosomal dominant fashion.  It is possible therefore that families labeled Setleis with an AD pattern of transmission actually have Brauer syndrome.  It should also be noted that the ablepharon-macrostonia syndrome (200110) and Barber-Say syndrome (209885) are also caused by mutations in TWIST2 and have some features in common with Setleis syndrome.

 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes

Marchegiani S, Davis T, Tessadori F, van Haaften G, Brancati F, Hoischen A, Huang H, Valkanas E, Pusey B, Schanze D, Venselaar H, Vulto-van Silfhout AT, Wolfe LA, Tifft CJ, Zerfas PM, Zambruno G, Kariminejad A, Sabbagh-Kermani F, Lee J, Tsokos MG, Lee CC, Ferraz V, da Silva EM, Stevens CA, Roche N, Bartsch O, Farndon P, Bermejo-Sanchez E, Brooks BP, Maduro V, Dallapiccola B, Ramos FJ, Chung HY, Le Caignec C, Martins F, Jacyk WK, Mazzanti L, Brunner HG, Bakkers J, Lin S, Malicdan MC, Boerkoel CF, Gahl WA, de Vries BB, van Haelst MM, Zenker M, Markello TC. Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes. Am J Hum Genet. 2015 Jul 2;97(1):99-110.

PubMed ID: 
26119818
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