Pycnodysostosis: Difference between revisions

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{{Infobox medical condition (new)
{{SI}}
{{Infobox medical condition
| name            = Pycnodysostosis
| name            = Pycnodysostosis
| synonyms        =
| image          = [[File:Pycnodysostosis_1.jpg|250px]]
| image          = Autosomal recessive - en.svg
| caption        = X-ray of a patient with pycnodysostosis showing characteristic features
| alt            =  
| synonyms        = [[Marble bone disease]], [[osteopetrosis acro-osteolytica]]
| caption        = Pycnodysostosis is inherited in an autosomal recessive manner
| pronounce      =  
| pronounce      =  
| field          =  
| specialty      = [[Medical genetics]], [[Orthopedics]]
| symptoms        =  
| symptoms        = [[Short stature]], [[osteosclerosis]], [[brittle bones]], [[dental abnormalities]], [[acro-osteolysis]]
| complications  =  
| complications  = [[Fractures]], [[dental caries]], [[sleep apnea]]
| onset          =  
| onset          = [[Childhood]]
| duration        =  
| duration        = [[Lifelong]]
| types          =  
| types          =  
| causes          =  
| causes          = [[Genetic mutation]] in the [[CTSK]] gene
| risks          =  
| risks          =  
| diagnosis      =  
| diagnosis      = [[Clinical examination]], [[genetic testing]]
| differential    =  
| differential    = [[Osteopetrosis]], [[cleidocranial dysostosis]], [[osteogenesis imperfecta]]
| prevention      =  
| prevention      =  
| treatment      =  
| treatment      = [[Orthopedic surgery]], [[dental care]], [[physical therapy]]
| medication      =  
| medication      =  
| prognosis      =  
| prognosis      = Generally good with management
| frequency      =  
| frequency      = Rare
| deaths          =  
| deaths          =  
}}
}}
'''Pycnodysostosis''' (from [[Greek language|Greek]]: πυκνός (puknos) meaning "dense",<ref>{{cite web|url=http://www.winternet.com/~chuckg/dictionary/dictionary.151.html|title=Dictionary of Botanical Epithets}}</ref> ''dys'' ("defective"), and ''ostosis'' ("condition of the bone")), is a [[lysosomal storage disease]] of the bone caused by a mutation in the gene that codes the [[enzyme]] [[cathepsin K]].<ref name="Pycnodysostosis">{{cite journal |pmid=8703060 |year=1996 |last1=Gelb |first1=BD |last2=Shi |first2=GP |last3=Chapman |first3=HA |last4=Desnick |first4=RJ |title=Pycnodysostosis, a lysosomal storage disease caused by cathepsin K deficiency |volume=273 |issue=5279 |pages=1236–1238 |journal=Science |doi=10.1126/science.273.5279.1236}}</ref>
{{Short description|A rare genetic disorder affecting bone density}}
 
'''Pycnodysostosis''' is a rare [[genetic disorder]] characterized by [[osteosclerosis]], or increased bone density, due to a defect in the [[cathepsin K]] gene. This condition leads to a variety of skeletal abnormalities and is inherited in an [[autosomal recessive]] pattern.
==Signs and symptoms==
==Signs and Symptoms==
Pycnodysostosis causes the bones to be abnormally dense ([[osteopetrosis]]); the last bones of the fingers (the distal [[phalanges]]) to be unusually short; and delays the normal closure of the connections ([[suture (anatomy)|sutures]]) of the skull bones in infancy, so that the "soft spot" ([[fontanelle]]) on top of the head remains widely open.<ref>{{cite journal |pmid=12125807 |year=2002 |last1=Motyckova |first1=G |last2=Fisher |first2=DE |title=Pycnodysostosis: role and regulation of cathepsin K deficiency in osteoclast function and human disease |volume=2 |issue=5 |pages=407–421 |journal=Current Molecular Medicine |doi=10.2174/1566524023362401}}</ref>
Individuals with pycnodysostosis typically present with short stature, delayed closure of the [[fontanelles]], and [[osteosclerosis]]. Other common features include:
 
* [[Craniofacial abnormalities]] such as a prominent forehead, a small jaw ([[micrognathia]]), and a high-arched palate.
Those with the syndrome have brittle bones which easily [[Bone fracture|break]], especially in the legs and feet. The [[Mandible|jaw]] and [[collar bone]] (clavicle) are also particularly prone to fractures.
* [[Dental abnormalities]], including delayed eruption of teeth and dental crowding.
 
* [[Brittle bones]] that are prone to fractures.
Other abnormalities involve the head and face, teeth, collar bones, skin, and nails. The front and back of the head are prominent. Within the open sutures of the skull, there may be many small bones (called [[wormian bones]]). The midface is less full than usual. The nose is prominent. The jaw can be small. The palate is narrow and grooved. The baby teeth are late coming in and may be lost much later than usual. The permanent teeth can also be slow to appear. The permanent teeth are commonly irregular and teeth may be missing ([[hypodontia]]). The collar bones are often underdeveloped and malformed. The skin over the back of the fingers is very wrinkled. The nails are flat and grooved.
* [[Clubbing of fingers]] and [[nail dysplasia]].
 
* [[Hypoplasia]] of the distal phalanges, leading to [[acro-osteolysis]].
Pycnodysostosis also causes problems that may become evident with time. Aside from the broken bones, the distal phalanges and the collar bone can undergo slow progressive deterioration. Vertebral defects may permit the spine to curve laterally resulting in [[scoliosis]]. The dental problems often require orthodontic care and [[dental caries|cavities]] are common.
 
==Genetics==
==Genetics==
This is an [[autosomal recessive]] [[osteochondrodysplasia]] that maps to chromosome 1q21.<ref name="Pycnodysostosis"/> Deficiency of Cathepsin K, a cysteine protease in [[osteoclasts]], is known to cause this condition. Cathepsin K became a much sought-after drug target in [[osteoporosis]] after the cause of pycnodysostosis was discovered. The disease consistently causes short stature. The height of adult males with the disease is less than {{convert|150|cm|abbr=on}}. Adult females with the syndrome are even shorter.
Pycnodysostosis is caused by mutations in the [[CTSK]] gene, which encodes the enzyme [[cathepsin K]]. This enzyme is crucial for the normal breakdown of [[collagen]] in the bone matrix. Mutations in this gene lead to impaired bone resorption, resulting in the characteristic increased bone density and fragility.
 
The disease is also known as Toulouse-Lautrec Syndrome, after the French artist [[Henri de Toulouse-Lautrec]], who may have had the disease. In 1996, the defective gene responsible for pycnodysostosis was located, offering accurate diagnosis, carrier testing and a more thorough understanding of this disorder.
 
==Diagnosis==
==Diagnosis==
 
Diagnosis of pycnodysostosis is based on clinical evaluation, family history, and radiographic findings. [[X-rays]] typically show increased bone density, [[acro-osteolysis]], and [[delayed closure of cranial sutures]]. Genetic testing can confirm mutations in the [[CTSK]] gene.
Diagnosis of Pycnodysostosis is done using a number of tests. [[Medical imaging|Medical Imaging]] done using [[Radiology]] (or [[Radiography]]) is one route to the diagnosis of pycnodysostosis. [[Genetic testing]] for pycnodysostosis is also available.
==Management==
 
There is no cure for pycnodysostosis, and treatment focuses on managing symptoms and preventing complications. This may include:
{{Accuracy-section|date=April 2018}}
* [[Orthopedic surgery]] to manage fractures and skeletal deformities.
 
* [[Dental care]] to address dental abnormalities.
==Treatment==
* [[Growth hormone therapy]] in some cases to improve growth.
The treatment for pycnodysostosis is based on managing the symptoms. Treatment may include [[surgery]], dental procedures, and medications for pain.
* Regular monitoring by a multidisciplinary team including [[endocrinologists]], [[orthopedic surgeons]], and [[dentists]].
 
==Prognosis==
Specialists involved in the care of someone with pycnodysostosis may include:
The prognosis for individuals with pycnodysostosis varies. While the condition is associated with increased risk of fractures and dental issues, many individuals lead relatively normal lives with appropriate management.
* [[Orthopedist]]
==See also==
* [[Dentist]]
* [[Osteopetrosis]]
* [[Otolaryngologist]]
* [[Cathepsin K]]
* [[Orthodontist]]
* [[Genetic disorders]]
* [[Maxillofacial]] surgeon
* [[Autosomal recessive inheritance]]
 
[[Category:Genetic disorders]]
# [[CRISPR interference|CRISPR]] interference technique.
 
==Epidemiology==
The precise frequency of pycnodysostosis has not been determined. Pycnodysostosis can be classified in the large group of genetic diseases that are individually uncommon, but collectively important because of the sum of their numbers, and their heavy impact upon affected individuals.
 
==References==
<references/>
 
== External links ==
{{Medical resources
|  DiseasesDB      =
|  ICD10          = Q78.8
|  ICD9            =
|  ICDO            =
|  OMIM            = 265800
|  MedlinePlus    =
|  eMedicineSubj  =
|  eMedicineTopic  =
|  MeshID          = D058631
|  Orphanet        = 763
}}
* [http://www.hideandseek.org/ Hide & Seek Foundation For Lysosomal Disease Research]
 
{{Osteochondropathy |state=autocollapse}}
 
[[Category:Autosomal recessive disorders]]
[[Category:Lysosomal storage diseases]]
[[Category:Rare diseases]]
[[Category:Rare diseases]]
<gallery>
[[Category:Skeletal disorders]]
File:Pycnodysostosis_1.jpg|Pycnodysostosis
File:Pycnodysostosis_5.jpg|Pycnodysostosis
File:Pycnodysostosis_6.jpg|Pycnodysostosis
File:Autosomal_recessive_-_en.svg|Autosomal recessive inheritance pattern
</gallery>

Latest revision as of 06:07, 8 April 2025

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
Founder, WikiMD Wellnesspedia &
W8MD's medical weight loss NYC, sleep center NYC
Philadelphia medical weight loss and Philadelphia sleep clinics

Pycnodysostosis
File:Pycnodysostosis 1.jpg
Synonyms Marble bone disease, osteopetrosis acro-osteolytica
Pronounce
Specialty Medical genetics, Orthopedics
Symptoms Short stature, osteosclerosis, brittle bones, dental abnormalities, acro-osteolysis
Complications Fractures, dental caries, sleep apnea
Onset Childhood
Duration Lifelong
Types
Causes Genetic mutation in the CTSK gene
Risks
Diagnosis Clinical examination, genetic testing
Differential diagnosis Osteopetrosis, cleidocranial dysostosis, osteogenesis imperfecta
Prevention
Treatment Orthopedic surgery, dental care, physical therapy
Medication
Prognosis Generally good with management
Frequency Rare
Deaths


A rare genetic disorder affecting bone density


Pycnodysostosis is a rare genetic disorder characterized by osteosclerosis, or increased bone density, due to a defect in the cathepsin K gene. This condition leads to a variety of skeletal abnormalities and is inherited in an autosomal recessive pattern.

Signs and Symptoms[edit]

Individuals with pycnodysostosis typically present with short stature, delayed closure of the fontanelles, and osteosclerosis. Other common features include:

Genetics[edit]

Pycnodysostosis is caused by mutations in the CTSK gene, which encodes the enzyme cathepsin K. This enzyme is crucial for the normal breakdown of collagen in the bone matrix. Mutations in this gene lead to impaired bone resorption, resulting in the characteristic increased bone density and fragility.

Diagnosis[edit]

Diagnosis of pycnodysostosis is based on clinical evaluation, family history, and radiographic findings. X-rays typically show increased bone density, acro-osteolysis, and delayed closure of cranial sutures. Genetic testing can confirm mutations in the CTSK gene.

Management[edit]

There is no cure for pycnodysostosis, and treatment focuses on managing symptoms and preventing complications. This may include:

Prognosis[edit]

The prognosis for individuals with pycnodysostosis varies. While the condition is associated with increased risk of fractures and dental issues, many individuals lead relatively normal lives with appropriate management.

See also[edit]