Marden–Walker syndrome is a rare autosomal

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...

 recessive congenital disorder

Congenital disorder

A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...

. It is characterized by blepharophimosis

Blepharophimosis

Blepharophimosis is a condition where the patient has bilateral ptosis with reduced lid size, vertically and horizontally. The nasal bridge is flat and there is hypoplastic orbital rim...

, microcephaly

Microcephaly

Microcephaly is a neurodevelopmental disorder in which the circumference of the head is more than two standard deviations smaller than average for the person's age and sex. Microcephaly may be congenital or it may develop in the first few years of life...

, micrognathia, multiple joint

Joint

A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...

 contracture

Contracture

A muscle contracture is a permanent shortening of a muscle or joint.. It is usually in response to prolonged hypertonic spasticity in a concentrated muscle area, such as is seen in the tightest muscles of people with conditions like spastic cerebral palsy....

s, arachnodactyly

Arachnodactyly

Arachnodactyly or achromachia, is a condition in which the fingers are abnormally long and slender in comparison to the palm of the hand...

, camptodactyly

Camptodactyly

Camptodactyly is a medical condition involving fixed flexion deformity of the interphalangeal joints of the little finger. This involves permanent flexure of one or more phalanges...

, kyphoscoliosis

Kyphoscoliosis

Kyphoscoliosis describes an abnormal curvature of the spine in both a coronal and sagittal plane. It is a combination of kyphosis and scoliosis. Kyphoscoliosis is a musculoskeletal disorder causing chronic underventilation of the lungs and may be one of the major causes of pulmonary hypertension...

, and delayed motor development and is often associated with cystic dysplastic kidney

Kidney

The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...

s, dextrocardia

Dextrocardia

Dextrocardia is a congenital defect in which the heart is situated on the right side of the body. There are two main types of dextrocardia: dextrocardia of embryonic arrest and dextrocardia situs inversus...

, Dandy-Walker malformation, and agenesis of corpus callosum

Agenesis of the corpus callosum

Agenesis of the corpus callosum is a rare birth defect in which there is a complete or partial absence of the corpus callosum. Agenesis of the corpus callosum occurs when the corpus callosum, the band of white matter connecting the two hemispheres in the brain, fails to develop normally,...

".

Pathophysiology

Though the pathomechanism of Marden-Walker syndrome is unknown, it may be caused by a genetic defect which manifests as a dysfunctional molecular mechanism

Ciliopathy

A ciliopathy is a genetic disorder of the cellular cilia or the cilia anchoring structures, the basal bodies, or of ciliary function.Although ciliopathies are usually considered to involve proteins that localize to the primary cilia or centrosomes, it is possible for ciliopathies to be associated...

 in the primary cilia structures of the cell

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

. These organelle

Organelle

In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer....

s are present in many cellular types throughout the human

Human

Humans are the only living species in the Homo genus...

 body. The cilia defects adversely affect "numerous critical developmental signaling pathways" essential to cellular development.

Genetics

MWS is inherited in an autosomal recessive manner. This means the defective gene responsible for the disorder is located on an autosome

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...

, and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry

Genetic carrier

A genetic carrier , is a person or other organism that has inherited a genetic trait or mutation, but who does not display that trait or show symptoms of the disease. They are, however, able to pass the gene onto their offspring, who may then express the gene...

one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder.