Acropectoral syndrome
Encyclopedia
Acropectoral syndrome is an autosomal
dominant skeletal dysplasia syndrome
affecting the hand
s, feet, sternum, and lumbosacral spine
. A recently proposed candidate gene
for preaxial polydactyly
is LMBR1
, encoding a novel
transmembrane receptor, which may be an upstream regulator of SHH
. The LMBR1 gene is on human chromosome
7q36.
SUMMARY
Other names for acropectoral syndrome include ACRPS, Syndactyly
, preaxial polydactyly and sternal deformity, and ACRP syndrome (3). This syndrome
is characterized by syndactyly
of all fingers/toes, pre axial polydactyly
in the hands/feet, and upper sternum
malformations. More specifically affected individuals show soft tissue syndactyly
of all fingers and toes (4). 14 out of the 22 individuals had pre axial polydactyly
, as well had a blind-ending U-shaped sinus
in the chest
wall or a prominent upper sternum
. Other symptoms included an extra big toe and an extra thumb (6). Treatment of individuals affected with this syndrome include oral pathology
, facial and limb plastic surgery
, and pediatric otolaryngology
(7). This syndrome
is different than acropectorovertebral dysplasia because the vertebral anomalies seen in acropectorovertebral dysplasia were not observed in these patients. This syndrome also differed from acropectorovertebral dysplasia because of the carpal, tarsal
, and metatarsal synostoses as well as the preaxial polydactyly
that occurred in the feet as well as in the hands. Soft tissue syndactyly
was more prominent that in acropectorovertebral dysplasia (5). The limb
defects seen in acrpectoral syndrome are also similar to those that occur in other dominantly inherited types of preaxial polydactyly, including preaxial polydactyly type II (PPD2), preaxial polydactyly type III (PPD3) and triphalangeal thumb- polysyndactyly (TPT-PS) (1). Acropectoral syndrome is autosomal dominant and best described in 22 patients of a Turkish family spanning six generations. The prevalence
of this disease is less than 1 in 1 million (4).
MAPPING
The cytogenetic location is 7q36 and genomic coordinates are GRCh37:147,900,000 - 159,138,663 (NCBI). Mapping of this syndrome was done by Dundar and coworkers in 2001. They showed that this phenotype
was linked to a 6.4-cM region of 7q36 flanked by the EN2 gene
and the marker D7S2423 (5). Dundar and coworkers characterized and mapped acropectoral syndrome and also showed it was unrelated to acropectorovertebral syndrome. The mapping showed that the acropectoral locus
was in a region where preaxial polydactyly
and triphalangeal thumb-polysyndactyly had previously been mapped. This study was important because it expanded the range of phenotypes that are connected to this locus
. Previously, preaxial polydactyly
and sternal defects have been linked to ectopic expression of the gene
Sonic hedgehog Shh
in limbbud and lateral plate mesoderm
during development
in mice. Dundar and coworkers found that the LMBR1 gene
links to pre axial polydactyly
. This gene encodes for a new transmembrane receptor and it is proposed that this receptor is an upstream regulator of SHH
(1).
CLINICAL FEATURES
All 22 individuals studied had partial or complete webbing of the soft tissue between their fingers and toes. In 13 of the individuals the most lateral 3 or 4 toes were flexed at the interphalangeals joints. According to Dundar and coworkers, 8 of the 22 individuals had “pre axial polydactyly
in the hands (unilateral in two, bilateral in six), ranging in severity
from broad or bifid distal phalanges in the thumbs to duplication of an entire biphalangeal or triphalangeal thumb, in two cases with an associated extra metacarpal, lying in a soft tissue web between the thumb and index finger. Fourteen had preaxial polydactyly
in the feet (unilateral in one, bilateral in 13), consisting of a small extra biphalangeal toe, in most cases with an associated rudimentary extra metatarsal, lying in a soft tissue web between the hallux
and second toe. In some cases, this was accompanied by hypoplasia
of the head of the first metatarsal and absence of both phalanges of the hallux
. In addition, 14 had a sternal abnormality, consisting of a pectus
carinatum deformity of the upper sternum
and/or a pectus
excavatum deformity of the lower sternum
, producing a blind ending, inverted U shaped sinus
in the anterior chest
wall. A thoracic CT scan of V.38, who was typically affected, showed an increase in the anterior-posterior diameter of the upper chest, with no underlying bony defect in the sternum
. There were no other skeletal or extraskeletal abnormalities” (1).
SUPPORT
Three main support groups of this syndrome are the ASGA in Australia, The Association for Children with Genetic Disorders in Poland, and the Association of People of Genetic Disorders in Greece (4). For more information: http://rarediseases.info.nih.gov/GARD/Condition/8485/Acropectoral_syndrome.aspx
Autosome
An autosome is a chromosome that is not a sex chromosome, or allosome; that is to say, there is an equal number of copies of the chromosome in males and females. For example, in humans, there are 22 pairs of autosomes. In addition to autosomes, there are sex chromosomes, to be specific: X and Y...
dominant skeletal dysplasia syndrome
Syndrome
In medicine and psychology, a syndrome is the association of several clinically recognizable features, signs , symptoms , phenomena or characteristics that often occur together, so that the presence of one or more features alerts the physician to the possible presence of the others...
affecting the hand
Hand
A hand is a prehensile, multi-fingered extremity located at the end of an arm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs...
s, feet, sternum, and lumbosacral spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
. A recently proposed candidate gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
for preaxial polydactyly
Polydactyly
Polydactyly or polydactylism , also known as hyperdactyly, is a congenital physical anomaly in humans, dogs, and cats having supernumerary fingers or toes....
is LMBR1
LMBR1
Limb region 1 protein homolog is a protein that in humans is encoded by the LMBR1 gene.-Further reading:...
, encoding a novel
Novel
A novel is a book of long narrative in literary prose. The genre has historical roots both in the fields of the medieval and early modern romance and in the tradition of the novella. The latter supplied the present generic term in the late 18th century....
transmembrane receptor, which may be an upstream regulator of SHH
SHH
SHH can refer to:* Summer Heights High, an Australian TV series* Sonic hedgehog, an important protein during vertebrate organogenesis* Students Helping Honduras, an international non-governmental organization operating in the U.S. and Honduras...
. The LMBR1 gene is on human chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
7q36.
Other names for acropectoral syndrome include ACRPS, Syndactyly
Syndactyly
Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, such as the siamang and kangaroo, but is an unusual condition in humans.-Classification:...
, preaxial polydactyly and sternal deformity, and ACRP syndrome (3). This syndrome
Syndrome
In medicine and psychology, a syndrome is the association of several clinically recognizable features, signs , symptoms , phenomena or characteristics that often occur together, so that the presence of one or more features alerts the physician to the possible presence of the others...
is characterized by syndactyly
Syndactyly
Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, such as the siamang and kangaroo, but is an unusual condition in humans.-Classification:...
of all fingers/toes, pre axial polydactyly
Polydactyly
Polydactyly or polydactylism , also known as hyperdactyly, is a congenital physical anomaly in humans, dogs, and cats having supernumerary fingers or toes....
in the hands/feet, and upper sternum
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...
malformations. More specifically affected individuals show soft tissue syndactyly
Syndactyly
Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, such as the siamang and kangaroo, but is an unusual condition in humans.-Classification:...
of all fingers and toes (4). 14 out of the 22 individuals had pre axial polydactyly
Polydactyly
Polydactyly or polydactylism , also known as hyperdactyly, is a congenital physical anomaly in humans, dogs, and cats having supernumerary fingers or toes....
, as well had a blind-ending U-shaped sinus
Sinus
- Anatomy :In anatomy, where a sinus is a sac or cavity in any organ or tissue:*Sinus , description of the general term*Paranasal sinuses, air cavities in the cranial bones, especially those near the nose, including:...
in the chest
Chest
The chest is a part of the anatomy of humans and various other animals. It is sometimes referred to as the thorax or the bosom.-Chest anatomy - Humans and other hominids:...
wall or a prominent upper sternum
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...
. Other symptoms included an extra big toe and an extra thumb (6). Treatment of individuals affected with this syndrome include oral pathology
Pathology
Pathology is the precise study and diagnosis of disease. The word pathology is from Ancient Greek , pathos, "feeling, suffering"; and , -logia, "the study of". Pathologization, to pathologize, refers to the process of defining a condition or behavior as pathological, e.g. pathological gambling....
, facial and limb plastic surgery
Plastic surgery
Plastic surgery is a medical specialty concerned with the correction or restoration of form and function. Though cosmetic or aesthetic surgery is the best-known kind of plastic surgery, most plastic surgery is not cosmetic: plastic surgery includes many types of reconstructive surgery, hand...
, and pediatric otolaryngology
Otolaryngology
Otolaryngology or ENT is the branch of medicine and surgery that specializes in the diagnosis and treatment of ear, nose, throat, and head and neck disorders....
(7). This syndrome
Syndrome
In medicine and psychology, a syndrome is the association of several clinically recognizable features, signs , symptoms , phenomena or characteristics that often occur together, so that the presence of one or more features alerts the physician to the possible presence of the others...
is different than acropectorovertebral dysplasia because the vertebral anomalies seen in acropectorovertebral dysplasia were not observed in these patients. This syndrome also differed from acropectorovertebral dysplasia because of the carpal, tarsal
Tarsal
Tarsal could refer to:*tarsus *tarsus *superior tarsal muscle...
, and metatarsal synostoses as well as the preaxial polydactyly
Polydactyly
Polydactyly or polydactylism , also known as hyperdactyly, is a congenital physical anomaly in humans, dogs, and cats having supernumerary fingers or toes....
that occurred in the feet as well as in the hands. Soft tissue syndactyly
Syndactyly
Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, such as the siamang and kangaroo, but is an unusual condition in humans.-Classification:...
was more prominent that in acropectorovertebral dysplasia (5). The limb
Limb (anatomy)
A limb is a jointed, or prehensile , appendage of the human or other animal body....
defects seen in acrpectoral syndrome are also similar to those that occur in other dominantly inherited types of preaxial polydactyly, including preaxial polydactyly type II (PPD2), preaxial polydactyly type III (PPD3) and triphalangeal thumb- polysyndactyly (TPT-PS) (1). Acropectoral syndrome is autosomal dominant and best described in 22 patients of a Turkish family spanning six generations. The prevalence
Prevalence
In epidemiology, the prevalence of a health-related state in a statistical population is defined as the total number of cases of the risk factor in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population...
of this disease is less than 1 in 1 million (4).
MAPPING
The cytogenetic location is 7q36 and genomic coordinates are GRCh37:147,900,000 - 159,138,663 (NCBI). Mapping of this syndrome was done by Dundar and coworkers in 2001. They showed that this phenotype
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
was linked to a 6.4-cM region of 7q36 flanked by the EN2 gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
and the marker D7S2423 (5). Dundar and coworkers characterized and mapped acropectoral syndrome and also showed it was unrelated to acropectorovertebral syndrome. The mapping showed that the acropectoral locus
Locus
The word locus is Latin for "place". It can mean:-Positions:*Locus of control, in industrial psychology, having an internal or external locus of control...
was in a region where preaxial polydactyly
Polydactyly
Polydactyly or polydactylism , also known as hyperdactyly, is a congenital physical anomaly in humans, dogs, and cats having supernumerary fingers or toes....
and triphalangeal thumb-polysyndactyly had previously been mapped. This study was important because it expanded the range of phenotypes that are connected to this locus
Locus
The word locus is Latin for "place". It can mean:-Positions:*Locus of control, in industrial psychology, having an internal or external locus of control...
. Previously, preaxial polydactyly
Polydactyly
Polydactyly or polydactylism , also known as hyperdactyly, is a congenital physical anomaly in humans, dogs, and cats having supernumerary fingers or toes....
and sternal defects have been linked to ectopic expression of the gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
Sonic hedgehog Shh
SHH
SHH can refer to:* Summer Heights High, an Australian TV series* Sonic hedgehog, an important protein during vertebrate organogenesis* Students Helping Honduras, an international non-governmental organization operating in the U.S. and Honduras...
in limbbud and lateral plate mesoderm
Mesoderm
In all bilaterian animals, the mesoderm is one of the three primary germ cell layers in the very early embryo. The other two layers are the ectoderm and endoderm , with the mesoderm as the middle layer between them.The mesoderm forms mesenchyme , mesothelium, non-epithelial blood corpuscles and...
during development
Development
-Land use:*Green development, a concept that includes consideration of community-wide or regional environmental implications*Land development, altering the landscape in any number of ways...
in mice. Dundar and coworkers found that the LMBR1 gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
links to pre axial polydactyly
Polydactyly
Polydactyly or polydactylism , also known as hyperdactyly, is a congenital physical anomaly in humans, dogs, and cats having supernumerary fingers or toes....
. This gene encodes for a new transmembrane receptor and it is proposed that this receptor is an upstream regulator of SHH
SHH
SHH can refer to:* Summer Heights High, an Australian TV series* Sonic hedgehog, an important protein during vertebrate organogenesis* Students Helping Honduras, an international non-governmental organization operating in the U.S. and Honduras...
(1).
CLINICAL FEATURES
All 22 individuals studied had partial or complete webbing of the soft tissue between their fingers and toes. In 13 of the individuals the most lateral 3 or 4 toes were flexed at the interphalangeals joints. According to Dundar and coworkers, 8 of the 22 individuals had “pre axial polydactyly
Polydactyly
Polydactyly or polydactylism , also known as hyperdactyly, is a congenital physical anomaly in humans, dogs, and cats having supernumerary fingers or toes....
in the hands (unilateral in two, bilateral in six), ranging in severity
Severity
Severity may refer to:* Severity , a canceled video game* a dimension for classifying seriousness for Technical support issues...
from broad or bifid distal phalanges in the thumbs to duplication of an entire biphalangeal or triphalangeal thumb, in two cases with an associated extra metacarpal, lying in a soft tissue web between the thumb and index finger. Fourteen had preaxial polydactyly
Polydactyly
Polydactyly or polydactylism , also known as hyperdactyly, is a congenital physical anomaly in humans, dogs, and cats having supernumerary fingers or toes....
in the feet (unilateral in one, bilateral in 13), consisting of a small extra biphalangeal toe, in most cases with an associated rudimentary extra metatarsal, lying in a soft tissue web between the hallux
Hallux
In tetrapods, the hallux is the innermost toe of the foot. Despite its name it may not be the longest toe on the foot of some individuals...
and second toe. In some cases, this was accompanied by hypoplasia
Hypoplasia
Hypoplasia is underdevelopment or incomplete development of a tissue or organ. Although the term is not always used precisely, it properly refers to an inadequate or below-normal number of cells. Hypoplasia is similar to aplasia, but less severe. It is technically not the opposite of hyperplasia...
of the head of the first metatarsal and absence of both phalanges of the hallux
Hallux
In tetrapods, the hallux is the innermost toe of the foot. Despite its name it may not be the longest toe on the foot of some individuals...
. In addition, 14 had a sternal abnormality, consisting of a pectus
Pectus
Pectus may refer to:* Pectus excavatum* Pectus carinatum...
carinatum deformity of the upper sternum
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...
and/or a pectus
Pectus
Pectus may refer to:* Pectus excavatum* Pectus carinatum...
excavatum deformity of the lower sternum
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...
, producing a blind ending, inverted U shaped sinus
Sinus
- Anatomy :In anatomy, where a sinus is a sac or cavity in any organ or tissue:*Sinus , description of the general term*Paranasal sinuses, air cavities in the cranial bones, especially those near the nose, including:...
in the anterior chest
Chest
The chest is a part of the anatomy of humans and various other animals. It is sometimes referred to as the thorax or the bosom.-Chest anatomy - Humans and other hominids:...
wall. A thoracic CT scan of V.38, who was typically affected, showed an increase in the anterior-posterior diameter of the upper chest, with no underlying bony defect in the sternum
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...
. There were no other skeletal or extraskeletal abnormalities” (1).
SUPPORT
Three main support groups of this syndrome are the ASGA in Australia, The Association for Children with Genetic Disorders in Poland, and the Association of People of Genetic Disorders in Greece (4). For more information: http://rarediseases.info.nih.gov/GARD/Condition/8485/Acropectoral_syndrome.aspx