View source for Morquio syndrome

{{Infobox medical condition (new)
| name          = Morquio syndrome
| image         = Mucopolysaccharidosis (Morquio's Disease) 1.jpg
| caption       = Patient with Morquio syndrome
| synonyms      = '''[[Mucopolysaccharidosis]] IV''', '''MPS IV''', '''Morquio-Brailsford syndrome''', or '''Morquio'''<ref name="MPSSoc IV">{{Cite web |title=MPS IV (Morquio syndrome) |url=http://mpssociety.org/mps/mps-iv-morquio/ |url-status=dead |archive-url=https://web.archive.org/web/20170821110949/http://mpssociety.org/mps/mps-iv-morquio/ |archive-date=21 August 2017 |access-date=14 January 2015 |website=MPSSociety.org |publisher=National MPS Society}}</ref>
| complications = Skeletal abnormalities, hearing loss, pulmonary failure, heart disease
| onset         = Birth; condition usually becomes apparent between ages 1 and 3
| duration      = Lifelong
| types         = Type A and Type B
| causes        = Inherited deficiency of enzymes
| risks         =
| diagnosis     =
| differential  =
| prevention    =
| treatment     = Elosulfase alfa (Vimizim) for Type A; no approved treatment for Type B
| medication    =
| prognosis     = Reduced lifespan. Usually death occurs in 20s to 30s
| frequency     = 1 in 200,000 to 1 in 300,000
| deaths        =
}}

'''Morquio syndrome''', also known as '''[[mucopolysaccharidosis]] type IV (MPS IV)''', is a rare [[metabolic disorder]] in which the body cannot process certain types of sugar molecules called [[glycosaminoglycans]] (AKA GAGs, or mucopolysaccharides). In Morquio syndrome, the specific GAG which builds up in the body is called [[keratan sulfate]]. This [[birth defect]], which is [[autosomal recessive]], is a type of [[lysosomal storage disorder]]. The buildup of GAGs in different parts of the body causes symptoms in many different organ systems.<ref name="Andrews">{{Cite book |last=James, William D. |title=Andrews' Diseases of the Skin: clinical Dermatology |last2=Berger |first2=Timothy G. |publisher=Saunders Elsevier |year=2006 |isbn=978-0-7216-2921-6}}</ref>{{rp|544}} In the US, the incidence rate for Morquio syndrome is estimated at between 1 in 200,000 and 1 in 300,000 live births.<ref name="MPSSoc IV" /><ref name="pmid18456538">{{Cite journal |vauthors=Prat C, Lemaire O, Bret J, Zabraniecki L, Fournié B |date=May 2008 |title=Morquio syndrome: Diagnosis in an adult |journal=Joint Bone Spine |volume=75 |issue=4 |pages=495–8 |doi=10.1016/j.jbspin.2007.07.021 |pmid=18456538}}</ref>

== Signs and symptoms ==

[[File:Corneal Clouding in MPS-VI (Maroteaux-Lamy Syndrome).jpg|thumb|right|Corneal clouding in a 30-year-old male with MPS VI. Morquio syndrome and other MPS disorders may also present with corneal clouding.]]
Patients with Morquio syndrome appear healthy at birth. Types A and B have similar presentations, but Type B generally has milder symptoms. The age of onset is usually between 1 and 3 years of age. Morquio syndrome causes progressive skeletal changes to the ribs and chest, which may lead to neurological complications such as nerve compression. Patients may also have hearing loss and clouded corneas. Intelligence is usually normal unless a patient has untreated [[hydrocephalus]].{{cn|date=November 2020}}

Physical growth slows and often stops around age 8. Skeletal abnormalities include a bell-shaped chest, widely spaced teeth with thin enamel, a flattening or curvature of the spine, shortened long bones, and dysplasia of the hips, knees, ankles, and wrists. The bones that stabilize the connection between the head and neck can be malformed (odontoid hypoplasia); in these cases, a surgical procedure called [[Spinal fusion|spinal cervical bone fusion]] can be lifesaving. These bone abnormalities often lead to abnormalities in gait and a tendency to fall. <ref>{{Cite book |last=Thoene |first=Jess G |title=Physicians' Guide to Rare Diseases |date=Jan 1, 1995 |publisher=Dowden Pub Co |isbn=978-0962871603 |page=216}}</ref> Restricted breathing, joint stiffness, and heart disease are also common. Children with the more severe form of MPS IV may not live beyond their twenties or thirties.{{citation needed|date=November 2020}}

Some additional signs and symptoms of Morquio syndrome include a short stature, [[scoliosis]], [[kyphosis]], hypermobile joints, [[knock-knees]], [[pectus carinatum]], misshapen limbs, unstable vertebrae, cord compression, [[hepatomegaly]], hearing problems, vision problems, and heart problems.<ref>{{Cite web |title=Morquio Syndrome |url=https://kidshealth.org/en/parents/morquio-syndrome.html |access-date=14 February 2023 |website=Nemours KidsHealth}}</ref>

==Cause==
Morquio syndrome is inherited from an [[autosomal recessive]] inherited gene. Every person has two copies of the genes needed to break down keratan sulfate, but only one healthy copy is needed. Both parents pass down one defective copy to their child, resulting in a child with no functional copies of the gene. As such, the body is incapable breaking down keratan sulfate for disposal. The incompletely broken down GAGs remain stored in cells in the body, causing progressive damage. Babies may show little sign of the disease, but as more and more cells become damaged, symptoms start to appear.<ref name="CanadianMPS">{{Cite web |title=MPS IV (Morquio Syndrome) |url=https://www.mpssociety.ca/education/what-is-mps/what-is-mps-iv/ |url-status=dead |archive-url=https://web.archive.org/web/20181111093253/https://www.mpssociety.ca/education/what-is-mps/what-is-mps-iv/ |archive-date=11 November 2018 |access-date=14 June 2019 |publisher=[[Canadian MPS Society]]}}</ref>

==Diagnosis==
=== Classification ===
This syndrome has two forms, A and B, referred to as Morquio A and Morquio B syndrome or MPS IVA and MPS IVB. The two forms are distinguished by the gene product involved; Type A involves a malfunction in the [[GALNS]] gene, while Type B involves a malfunction of the [[GLB1]] gene.{{citation needed|date=November 2020}}

{| class="wikitable"
|+ Genetics of MPS IV
! Morquio syndrome type !! Gene !! Missing enzyme !! Chromosomal region
|-
! Type A
| [[GALNS]] || [[Galactosamine-6 sulfatase]] || 16q24
|-
! Type B
| [[GLB1]] || [[Beta-galactosidase]] || 3p22
|}

==Treatment==
The treatment for Morquio syndrome consists of [[prenatal diagnosis|prenatal identification]] and of [[enzyme replacement therapy]]. On 12 February 2014, the [[US Food and Drug Administration]] approved the drug [[elosulfase alfa]] (Vimizim) for treating Type A. Currently, there is no treatment for Type B.<ref name="CanadianMPS" />

==Prognosis==
The lifespan of patients with Morquio syndrome is variable and depends on the subtype. Type A is generally severe, with a life expectancy in the 20s to 30s.<ref name="NINDS">{{Cite web |date=13 May 2019 |title=Mucopolysaccharidoses Fact Sheet |url=https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Mucopolysaccharidoses-Fact-Sheet |access-date=14 June 2019 |publisher=[[National Institute of Neurological Disorders and Stroke]]}}</ref> In 2016, a man with Morquio syndrome died at the age of 81.<ref>{{Cite web |last=Blacketer |first=Rosie |date=23 September 2016 |title=Kenneth Dean Martin |url=http://och-c.com/?q=content/kenneth-dean-martin |access-date=14 June 2019 |publisher=[[Osage County Herald-Chronicle]]}}</ref>

One study found that the mean life expectancy for patients in the [[United Kingdom]] was 25.30, with a [[standard deviation]] of 17.43 years. On average, female patients lived 4 years longer than male patients. [[Respiratory failure]] was the primary cause of death in 63% of patients. Other causes of death were cardiac failure (11%), post-traumatic organ failure (11%), complications of surgery (11%), and [[heart attack]] (4%). Life expectancy has been increasing since the 1980s. The average age at death due to respiratory failure improved from 17.42 years old in the 1980s to 30.74 years old in the 2000s.<ref name="Lavery">{{Cite journal |last=Lavery |first=Christine |last2=Hendriksz |first2=Chris |date=10 Apr 2014 |title=Mortality in Patients with Morquio Syndrome A |journal=[[Journal of Inherited Metabolic Disease]] |series=JIMD Reports |volume=15 |pages=59–66 |doi=10.1007/8904_2014_298 |pmc=4270860 |pmid=24718838}}</ref>

== History ==
The condition was first described, simultaneously and independently, in 1929, by [[Luis Morquio]] (1867–1935),<ref>{{Cite journal |last=Morquio |first=L. |year=1929 |title=Sur une forme de dystrophie osseuse familiale |journal=Archives de Médecine des Infants |location=Paris |volume=32 |pages=129–135 |issn=0365-4311}}</ref> a prominent [[Uruguay]]an physician who discovered it in [[Montevideo]], and [[James Frederick Brailsford]] (1888–1961), an English radiologist in [[Birmingham]], England.<ref>{{WhoNamedIt|synd|2108}}</ref><ref>{{Cite journal |last=Brailsford |first=J. F. |year=1929 |title=Chondro-osteo-dystrophy: Roentgenographic & clinical features of a child with dislocation of vertebrae |journal=American Journal of Surgery |location=New York |volume=7 |issue=3 |pages=404–410 |doi=10.1016/S0002-9610(29)90496-7}}</ref> They both recognized the occurrence of [[cornea]]l clouding, [[aorta|aortic]] valve disease, and urinary excretion of keratan sulfate. Morquio observed the disorder in four siblings in a family of Swedish descent and reported his observations in French.{{<<ref>ref>citation needed|date=November 2020</https://www.whonamedit.com/synd.cfm/2108.html></ref>}}

== See also ==
* [[Hurler syndrome]] ([[Mucopolysaccharidosis type I|MPS I]])
* [[Hunter syndrome]] (MPS II)
* [[Sanfilippo syndrome]] (MPS III)
* [[Dwarfism]]

== References ==
{{reflist}}

== External links ==
{{Medical resources
|   DiseasesDB     = 30807
|    ICD10          = {{ICD10|E|76|2|e|70}}
|   ICD9           = {{ICD9|277.5}}
|   ICDO           =
|   OMIM           = 253000
|   OMIM_mult      = {{OMIM|253010||none}}
|    MedlinePlus    = 001206
|   eMedicineSubj  = ped
|   eMedicineTopic = 1477
|   MeshID         = D009085
|   Orphanet       = 582
}}

{{Mucopolysaccharidoses}}

{{DEFAULTSORT:Morquio Syndrome Definition}}
[[Category:Autosomal recessive disorders]]
[[Category:Proteoglycan metabolism disorders]]
[[Category:Rare syndromes]]
[[Category:Diseases named after discoverers]]