Weissenbacher–Zweymuller syndrome (WZS), also called Pierre-Robin syndrome with fetal chondrodysplasia, is an

autosomal An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosome ...

recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and ...

congenital disorder A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

, linked to

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, ...

s (955 gly -> glu) in the '' COL11A2''

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

(located on

chromosomal A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most importa ...

position 6p21.3), which codes for the α₂ strand of

collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...

type XI. It is a

collagenopathy, types II and XI The type II and XI collagenopathies are a group of disorders that affect connective tissue, the tissue that supports the body's joints and organs. These disorders are caused by defects in type II or type XI collagen. Collagens are complex molecules ...

disorder. The condition was first characterized in 1964 by G. Weissenbacher and Ernst Zweymüller.

Presentation

The disorder causes facial abnormalities, skeletal malformation and occasionally

neural tube defect Neural tube defects (NTDs) are a group of birth defects in which an opening in the spine or cranium remains from early in human development. In the third week of pregnancy called gastrulation, specialized cells on the dorsal side of the embryo ...

s; the skeletal disfigurements resolve to a degree in the course of development. Mutations in different parts of the gene may lead to

deafness Deafness has varying definitions in cultural and medical contexts. In medical contexts, the meaning of deafness is hearing loss that precludes a person from understanding spoken language, an audiological condition. In this context it is writte ...

Stickler syndrome Stickler syndrome (hereditary progressive arthro-ophthalmodystrophy) is a group of rare genetic disorders affecting connective tissue, specifically collagen. Stickler syndrome is a subtype of collagenopathy, types II and XI. Stickler syndrome i ...

type III (

myopia Myopia, also known as near-sightedness and short-sightedness, is an eye condition where light from distant objects focuses in front of, instead of on, the retina. As a result, distant objects appear blurry, while close objects appear normal. ...

retinal detachment Retinal detachment is a condition where the retina pulls away from the tissue underneath it. It may start in a small area, but without quick treatment, it can spread across the entire retina, leading to serious vision loss and possibly blindness. ...

and skeletal abnormalities). Infants and children: Infants that are born with Weissenbacher-Zweymüller syndrome usually have short bones in their arms and legs.Genetics Home Reference. (2016). Retrieved from U.S. National Library of Medicine : https://medlineplus.gov/genetics/condition/weissenbacher-zweymuller-syndrome/ The thigh and upper arm bones are wider than usual resulting in a dumbbell-shape while the bones of the vertebrae may be abnormal. Typical abnormal facial features can be wide-set protruding eyes (hypertelorism), a small and upturned nose with a flat bridge, small jaw (micrognathia) and a cleft palate. Some infants have high-frequency hearing loss. Infants may also exhibit a psychomotor delay.OSMED, Heterozygous. (2006). Retrieved from National Organization for Rare Disorders: http://rarediseases.org/rare-diseases/osmed-heterozygous After the period of growth deficiency the individual makes improvements in bone growth leading to a normal physical development around age 5 or 6. Adults: Many with Weissenbacher-Zweymüller syndrome have a catch-up growth phase causing the adults to not be unusually short. Many adults still will have hearing loss and typical abnormal facial features of Weissenbacher-Zweymüller syndrome.

Causes

Dominant genetic disorders can be caused by just a single copy of an abnormal gene. This abnormal gene can be the result of being inherited from either parent or be a new mutation. Most cases are caused by a de novo (new) mutation in the gene that occurs during the formation of the egg or sperm. These cases occur when there is no history of the disorder in the family. The COL11A2 gene is responsible for providing instructions on making one component of the type XI collagen. Type XI collagen is a complex molecule that helps give structure and strength to the connective tissues. Collagen is found in bone. It is also found in cartilage that makes up most of the skeleton during early development. The mutation of COL11A2 in Weissenbacher-Zweymüller syndrome disrupts the assembly of the type XI collagen molecules. The malfunctioning collagen weakens the connective tissue causing impaired bone development. COL11A2 is also associated with autosomal dominant non-syndromic hearing loss (ADNSHL).Kim, S., Park, H., Sagong, B. et al. Genes Genom (2016). doi:10.1007/s13258-016-0440-4 All mutations of COL11A2 in ADNSHL are missense mutations.

Diagnosis

Weissenbacher-Zweymüller syndrome is diagnosed upon a thorough clinical evaluation, detailed patient history, identification of characteristic symptom and a variety of specialized tests which includes x-rays.

Treatment

Because there is no cure, treatment is directed towards the specific symptoms that are present in each individual.

Epidemiology

Weissenbacher-Zweymüller syndrome affects males and females in the same numbers. About 30 cases have been reported in medical literature. The disorder can be underdiagnosed causing no true frequency in the population.

References

External links

* {{DEFAULTSORT:Weissenbacher-Zweymuller syndrome Congenital disorders Autosomal recessive disorders Rare syndromes Collagen disease Syndromes affecting hearing Syndromes affecting bones Syndromes affecting the jaw Syndromes with craniofacial abnormalities Syndromes with cleft lip and/or palate Diseases named after discoverers