What are the other Names for this Condition? (Also known as/Synonyms)

• DBQD (Desbuquois Dysplasia)
• Desbuquois Dysplasia (DBQD)
• Micromelic Dwarfism, Narrow Chest, Vertebral and Metaphyseal Abnormalities and Advanced Carpotarsal Ossification

What is Desbuquois Syndrome? (Definition/Background Information)

• Desbuquois Syndrome (or Desbuquois Dysplasia or DBQD) is a rare type of osteochondrodysplasia (a disorder of the development of bones and cartilage)
• Characteristics may vary in severity and can include short stature with short extremities, severe joint laxity with dislocation, osteopenia, kyphoscoliosis, distinctive facial characteristics and other abnormalities
• Two forms have been distinguished on the basis of the presence (type 1) or the absence (type 2) of characteristic hand anomalies. Type 1 can be associated with severe respiratory problems 
• A variant form of DBQD, Kim variant, has been described in 7 patients originating from Korea and Japan, and is characterized by short stature, joint and minor facial anomalies, together with significant hand anomalies with short bones in the hands, long fingers and advanced bone age
• DBQD type 1 and Kim variant are caused by mutations in the gene CANT1.  Some cases of DBQD type 2 are caused by mutations in the gene XYLT1 but in other cases the cause is unknown. The disorder is inherited in an autosomal recessive manner
• Treatment for the condition is geared towards the signs and symptoms present in each individual

(Source: Desbuquois Syndrome;Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Desbuquois Syndrome? (Age and Sex Distribution)

• Desbuquois Syndrome is a rare congenital disorder. The presentation of symptoms may occur at birth

• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected
• The Kim Variant of Desbuquois Syndrome is reportedly observed among the Korean and Japanese community

What are the Risk Factors for Desbuquois Syndrome? (Predisposing Factors)

• A positive family history may be an important risk factor, since Desbuquois Syndrome can be inherited
• Currently, no other risk factors have been clearly identified for Desbuquois Syndrome 

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Desbuquois Syndrome? (Etiology)

• Desbuquois Syndrome type 1 and Kim variant are caused by mutations in the CANT1 gene (located on chromosome 17q25.3)
• In some cases of Desbuquois Syndrome type 2 there are mutations in the XYLT1 gene (located on chromosome16p12), but in other cases no cause has been identified, suggesting that there may be other unidentified genes that may also cause the condition
• Desbuquois Syndromeis inherited in an autosomal recessive manner

(Source: Desbuquois Syndrome;Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Autosomal recessive: Autosomal recessive conditions are traits or disorders that occur when two copies of an abnormal gene have been inherited on a non-sex chromosome. If both parents have an autosomal recessive condition, there is a 100% likelihood of passing on the mutated genes to their children. If, however, only one mutant copy of the gene is inherited, the individual will be a carrier of the condition, but will not be present with any symptoms. Children born to two carriers, have a 25% chance of being homozygous dominant (unaffected), a 50% chance of being heterozygous (carrier), and a 25% chance of being homozygous recessive (affected).

 What are the Signs and Symptoms of Desbuquois Syndrome?

The signs and symptoms of Desbuquois Syndrome may vary in type and severity, and may include:

• Intrauterine growth retardation
• Short stature with shortened extremities (arms and legs); adult stature is usually 114 cm or greater
• Generalized joint laxity, which can cause joint dislocations
• Radial deviation of the fingers with thumbs that are often broad and in the "hitchhiker position"
• Narrow chest with pectus carinatum (which can lead to respiratory infections)
• Kyphoscoliosis
• Distinctive facial characteristics including a round flat face, prominent eyes, micrognathia (small jaw), saddle nose, long upper lip, flat philtrum (area between the upper lip and nose), and short neck
• Intellectual disability of various degrees
• Obesity in adults

Signs and symptoms specific to Desbuquois Syndrome Type 1:

• Accessory ossification center situated away (distal) from the second bone of the hand (metacarpal)
• Bifid distal phalanx (the bone of the tip of the finger is divided in two parts), or thumb with delta-shaped phalanx)

Signs and symptoms specific to Desbuquois Syndrome, Kim Variant:

• Short metacarpals (bones of the hand) and fingers with long bones (elongated phalanges) with advanced carpal bone age

(Source: Desbuquois Syndrome;Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Desbuquois Syndrome Diagnosed?

Desbuquois Syndrome is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Desbuquois Syndrome?

The complications of Desbuquois Syndrome may include:

• Sleep apnea
• Frequent respiratory infections
• Strabismus
• Club foot
• Cleft palate
• Glaucoma
• Severe scoliosis
• Cryptorchidism (undescended testicle)

(Source: Desbuquois Syndrome;Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Desbuquois Syndrome Treated?

Only symptomatic treatment is currently available for individuals with Desbuquois Syndrome.

• Many people with the condition may present with respiratory problems at birth or during infancy and need urgent attention
• Severe scoliosis, a common complication, may be managed with physical therapy to control the progression of spine abnormalities
• Arthrodesis (surgical fusion of a joint) may be considered for dislocations
• Surgery may be considered for glaucoma
• Because of the degree of shortness in affected individuals, psychological support may be appropriate for some individuals

How can Desbuquois Syndrome be Prevented?

Currently, Desbuquois Syndrome may not be preventable, since it is a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Desbuquois Syndrome? (Outcomes/Resolutions)

• The prognosis of Desbuquois Syndrome is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Desbuquois Syndrome:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/