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Genetics of Mucopolysaccharidosis Type IV Follow-up

  • Author: Nancy E Braverman, MS, MD; Chief Editor: Maria Descartes, MD  more...
 
Updated: Mar 24, 2014
 

Further Outpatient Care

See the list below:

  • The authors recommend that patients with Morquio syndrome (mucopolysaccharidosis type IV) be evaluated yearly by a geneticist, who can supervise a multidisciplinary care approach.
  • Depending on the degree of atlantoaxial stability at the time of diagnosis, routine flexion or extension radiographs to monitor for subluxation are recommended.
  • A sleep study is recommended if signs of cervical myelopathy or obstructive apnea are present.
  • Ideally, patients with Morquio syndrome (mucopolysaccharidosis type IV) should be referred to an orthopedic surgeon at the time of diagnosis to evaluate for occult cervical instability, scoliosis, or kyphosis. The orthopedist should have experience in managing skeletal dysplasias because multiple orthopedic procedures may be required.
  • Ophthalmologic evaluations should be performed regularly.
  • Attention to daily oral hygiene and professional dental cleaning and evaluation every 6-12 months is necessary to minimize the effects of thin dental enamel.
  • Echocardiography should be performed to evaluate for valvular disease associated with mucopolysaccharide deposition; abnormalities should be monitored by a cardiologist.
  • All patients with Morquio syndrome (mucopolysaccharidosis type IV) should receive routine childhood vaccinations, as well as influenza and pneumococcal vaccines, because their chest and spine deformities predispose them to pulmonary infections. Guidelines for immunizations have been established.[8]
  • Audiology testing is recommended as needed. Guidelines for hearing assessment in infants and children have been established.[9]
  • Counseling may be beneficial in childhood and adolescence to help patients cope with the teasing or depression often associated with physical limitations and dysmorphic features.
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Further Inpatient Care

See the list below:

  • Admission for surgical interventions in patients with Morquio syndrome (mucopolysaccharidosis type IV) may be required (see Treatment). These procedures include femoral osteotomies, corrective knee surgery for severe genu valgus deformity, and cervical spinal fusion.
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Inpatient & Outpatient Medications

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  • Medications for supportive care, such as nonsteroidal anti-inflammatory drugs (NSAIDs) for joint pain, antibiotics for pulmonary infections, and oxygen for pulmonary compromise and obstructive sleep apnea, can be used to treat the manifestations of this disorder.
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Complications

Many potential complications exist for patients with Morquio syndrome (mucopolysaccharidosis type IV). They include the following:

  • Atlantoaxial instability
  • Skeletal abnormalities (see Physical) leading to subsequent difficulties with ambulation and pain
  • Cervical myelopathy
  • Pulmonary compromise
  • Valvular and coronary heart disease
  • Hearing deficits
  • Corneal clouding
  • Dental caries
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Prognosis

See the list below:

  • Patients with mild manifestations of Morquio syndrome (mucopolysaccharidosis type IV), regardless of type, have been reported to survive into the seventh decade of life.
  • Patients with severe manifestations, primarily related to cervical instability and pulmonary compromise, often do not survive beyond the second or third decade of life.
  • Length of survival may improve with the improved comprehensive care available to these patients today.
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Patient Education

Aside from their professional caregivers, several additional resources for patients with mucopolysaccharidosis exist, including Society for the Study of Inborn Errors of Metabolism, Online Mendelian Inheritance in Man, International Morquio Organization, National MPS Society, The National Organization for Rare Disorders, Inc, National Institute of Neurological Disorders and Stroke, and Little People of America, Inc.

This section was written for those individuals with a family member affected by Morquio syndrome (mucopolysaccharidosis type IV) and their healthcare providers. The authors have compiled information from families that have first-hand experience with Morquio syndrome (mucopolysaccharidosis type IV) in their everyday lives. The following information is not intended to be a formal study; it is simply information and suggestions from these families in response to several questions.

  • Examples of how the diagnosis was made and at what age include the following:
    • Age 8 months: This child was initially seen by an orthopedist for standing with bent knees. Later, more testing (not specified) was performed at a large institution and the diagnosis was made.
    • Age 14 months: The child was not crawling like her siblings. Her doctor performed a urine test, skin biopsy, and bone marrow aspirate to establish the diagnosis in 1964.
    • Age 1 year: The diagnosis was suspected from radiographs that were performed to evaluate this child's kyphosis and scoliosis. A blood test confirmed the diagnosis.
    • Age 3 years: Decreased growth rate was noted at a routine pediatric appointment. A radiologist noted abnormalities of the ends of the bones on MRI. A skin biopsy by a geneticist confirmed the diagnosis.
    • Age 3 years: After this child reported back pain, his pediatrician found a protrusion in his back. Referral to a geneticist who collected blood, urine, and a skin biopsy confirmed the diagnosis of Morquio syndrome (mucopolysaccharidosis type IV).
    • Age 4 years: This child was first seen by a geneticist to evaluate a skin lesion. The geneticist thought that her skeleton was consistent with Morquio syndrome (mucopolysaccharidosis type IV) and performed radiographic studies (skeletal survey) and a urine test for diagnosis.
    • Age 4 years: This child had little growth through age 2 years and none from age 3-4 years. After referral to an endocrinologist, hand radiographs revealed findings suggestive of mucopolysaccharidosis (MPS). A skin biopsy was performed to confirm the diagnosis.
  • Examples of common physical difficulties these patients have and their methods to overcome them include the following:
    • To avoid carrying heavy books to and from school, use 2 sets of textbooks; one for home and one for school.
    • For difficulty walking the same speed and distance of peers, try an electric scooter or tricycle at school, work, or home.
    • One person reports that his classmates pull him in a wagon to travel long distances at school.
    • A palm pilot or laptop computer can be used to take notes in school if weak wrists are a problem.
    • To participate in field trips, an adult family member of one affected individual always went along.
    • One technique that was nearly universal among all parents was to meet with school personnel at the beginning of each school year to explain Morquio syndrome (mucopolysaccharidosis type IV) and some of the physical limitations their children may have.
    • In college, one individual requested a ground floor dorm room, a lower rod in her closet, and a lower keyhole in her door.
  • The following are examples of social difficulties these patients experience and how they have managed them:
    • In addition to educating school administrators, teachers, and counselors about Morquio syndrome (mucopolysaccharidosis type IV), many families suggest meeting with the classmates of their affected children. These efforts reportedly increase the students' understanding of Morquio syndrome (mucopolysaccharidosis type IV) and the overall acceptance of their child.
    • One mother and her affected daughter have been on a local talk show to discuss Morquio syndrome (mucopolysaccharidosis type IV). They believe this project and their involvement in a local television show about Morquio syndrome (mucopolysaccharidosis type IV) have made acceptance of the affected daughter in their community much easier.
  • Other medical concerns families reported and how they are managed include the following:
    • Dental: Several individuals reported hypoplastic (thin, weak, poorly formed) tooth enamel and cavities. Braces were difficult for some because of the thin tooth enamel, and the teeth required capping. Some have formal dental cleaning every 3 months with annual or biannual fluoride treatments to help prevent cavities.
    • Aural: Only a few individuals required hearing aids for various degrees of hearing loss. Most denied difficulties in this area.
    • Cardiac: No one reported any heart abnormalities that required surgery or medications. In general, those that responded are evaluated by a cardiologist with echocardiography every 1-2 years.
    • Ocular: Nearly everyone reported some degree of corneal clouding, but no one thought that his or her vision was severely impaired by it.
    • Skeletal: Several people with Morquio syndrome (mucopolysaccharidosis type IV) reported that they have had cervical spine fusion; some had surgery after neurologic symptoms were present, whereas others underwent the procedure before any neurologic complications. Hip surgery was another common procedure reported by these patients. Several patients also reported joint laxity and pain, primarily in the knees, ankles, and wrists. They managed these problems with plastic braces and adaptive tools in the kitchen to compensate for their weak grip. Most avoided carrying heavy objects. One individual reported that she now has increasing stiffness in her elbows that she treats with warm water.
    • Surgical: The universal recommendation from individuals with Morquio syndrome (mucopolysaccharidosis type IV) and their families is to request an anesthesiologist experienced in skeletal dysplasias and pediatrics.
  • Patients with Morquio syndrome (mucopolysaccharidosis type IV) had similar routine health schedules, as follows:
    • Consultation with a pediatric neurologist, orthopedist, and primary care physician every 6 months
    • Yearly eye, ear, and cardiology evaluation
    • Yearly visit to neurologist and spine surgeon with annual hearing examination
    • Biannual eye examination and dental appointment
    • Evaluation with an orthopedist every 6 months and a pediatric cardiologist, ophthalmologist, and otolaryngologist once every year
    • Consultation with a pediatrician as needed, orthopedist every 6 months, dentist every 3 months, ophthalmologist every 6-12 months, and cardiologist every 1-2 years
    • Yearly neck, spine, and hip radiographs with yearly eye examinations
  • Below is advice from people with Morquio syndrome (mucopolysaccharidosis type IV) and their families:
    • To the family of a newly diagnosed individual
      • "Each person is different. [The person with Morquio syndrome] did not develop a lot of the problems we were told she would."
      • "When we received the diagnosis, we decided that this was part of her life—not her life."
      • "Assume your child can live a normal life. Help your child get solid education and be active socially."
      • "Each case is different! There are all different levels of severity. Take one day at a time. Get a good medical team."
      • "Keep things as "normal" as possible, but take extra measures for small children to be gentle with a Morquio child."
      • "I never discourage him from doing anything unless it jeopardizes his health or his body. I expect him to finish school and go to college just like my daughter."
    • To the physicians treating patients with Morquio syndrome (mucopolysaccharidosis type IV)
      • "Find out what experts say. Read literature, but also talk to other physicians and researchers about Morquio."
      • "Please listen to the family. We may not be physicians, but we can tell you about our child."
      • "Work as a team. Involve the parents in every step of their child's care. Don't treat parents with an air of superiority. Teach and help them as much as possible."
    • To other newly diagnosed individuals
      • "Find at least one physician that knows Morquio [syndrome] to oversee care at least once a year. Find other families and join Little People of America and The National MPS Society. Read their newsletters, see their web sites, and go to their conferences."
      • "Be aware of the potential problems and your own limitations. Do not let the diagnosis dictate who you are or how you live your life."
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Contributor Information and Disclosures
Author

Nancy E Braverman, MS, MD Associate Professor, Department of Human Genetics, McGill University

Nancy E Braverman, MS, MD is a member of the following medical societies: Alpha Omega Alpha, Society for Inherited Metabolic Disorders, Society for the Study of Inborn Errors of Metabolism, American Society of Human Genetics

Disclosure: Nothing to disclose.

Coauthor(s)

Julie Hoover-Fong, MD, PhD, FACMG Associate Professor, Director, Greenberg Center for Skeletal Dysplasias, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine

Julie Hoover-Fong, MD, PhD, FACMG is a member of the following medical societies: American College of Medical Genetics and Genomics, International Skeletal Dysplasia Society, American Society of Human Genetics

Disclosure: Nothing to disclose.

Michael C Ain, MD Associate Professor, Departments of Neurosurgery and General Surgery, Division of Pediatric Orthopaedic Surgery, Johns Hopkins University School of Medicine

Michael C Ain, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Association, Scoliosis Research Society, Pediatric Orthopaedic Society of North America

Disclosure: Nothing to disclose.

Shunji Tomatsu, MD, PhD Professor, Department of Pediatrics, Saint Louis University School of Medicine

Shunji Tomatsu, MD, PhD is a member of the following medical societies: National MPS Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Margaret M McGovern, MD, PhD Professor and Chair of Pediatrics, Stony Brook University School of Medicine

Margaret M McGovern, MD, PhD is a member of the following medical societies: American Academy of Pediatrics, American Society of Human Genetics

Disclosure: Nothing to disclose.

Chief Editor

Maria Descartes, MD Professor, Department of Human Genetics and Department of Pediatrics, University of Alabama at Birmingham School of Medicine

Maria Descartes, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Medical Genetics and Genomics, American Medical Association, American Society of Human Genetics, Society for Inherited Metabolic Disorders, International Skeletal Dysplasia Society, Southeastern Regional Genetics Group

Disclosure: Nothing to disclose.

Additional Contributors

Karl S Roth, MD Retired Professor and Chair, Department of Pediatrics, Creighton University School of Medicine

Karl S Roth, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Nutrition, American Pediatric Society, American Society for Nutrition, American Society of Nephrology, Association of American Medical Colleges, Medical Society of Virginia, New York Academy of Sciences, Sigma Xi, Society for Pediatric Research, Southern Society for Pediatric Research

Disclosure: Nothing to disclose.

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Lateral view of spine in a child aged 8 years and 7 months. This radiograph shows advanced platyspondyly, irregularity, and anterior beaking of vertebral bodies characteristic of dysostosis multiplex. Note also the gibbus deformity and lordosis, which are characteristic of Morquio syndrome.
Cervical spine, flexion and extension views, in a child aged 5 years and 11 months. These flexion and extension images depict anterior and posterior subluxation, respectively, of the atlas secondary to odontoid hypoplasia.
Bilateral lower extremity views in a patient aged 22 years and 6 months. Metaphyseal irregularities and the characteristic genu valgus deformity are easily observed in this image.
Bilateral hand radiographs in a patient aged 22 years and 6 months. Note the tapering of the proximal portion of metacarpals 2 through 5 and small irregular carpal bones. The epiphyseal involvement characteristic of Morquio syndrome is exemplified by the tapered irregular distal radius and ulna. Overall, the bones are osteopenic with cortical thinning.
Upper extremities in a child aged 6 years and 11 months. Note the irregular epiphyses and widened metaphyses. Cortical thinning and mild widening of the diaphysis of the humerus are visible.
Multiple abnormalities are present in the pelvis, including dysplastic femoral heads and oblique acetabular roof with coxa valgus deformity. Flared iliac wings usually observed in Morquio syndrome are not well represented in this radiograph.
Anteroposterior view of the chest in a child aged 8 years and 4 months with Morquio syndrome. To reference the relatively small size of this chest, this patient's vital capacity was 500 cc, but the expected value based on height and weight was 1400 cc. Widened metaphyses and irregular epiphyses of the humeri and generalized platyspondyly are present. Oar-shaped ribs (widening ribs anteriorly and narrowing at the vertebrae) are easily observed and are another key characteristic of dysostosis multiplex.
Defects in keratan sulfate (KS) degradation resulting in Morquio syndrome.
The individual on the front of the scooter is 19 years old and has Morquio syndrome. Her friend on the back is an average-stature 10 year old without Morquio syndrome. On the driver, note the enlargement at the knees and the wrist deformity. Also, note the successful adaptation of the scooter to ambulate.
Note the short trunk and protuberant rib structure in this child with Morquio syndrome. More importantly, notice that Morquio syndrome is not preventing this child from being active and fishing.
Table 1. Clinical and Biochemical Features Distinguishing the Mucopolysaccharidoses and Morquio Syndrome (Mucopolysaccharidosis Type IV)
MPS TypeEponymDeficient



Enzyme



Neuro-degenerationSomatic Features*Corneal CloudingBone / Joint AbnormalityMucopoly-saccharide Stored
IHHurlerα -iduronidase++++++++++Dermatan sulfate (DS), heparan sulfate (HS)
IH/SHurler-Scheieα -iduronidase++++++DS, HS
ISScheieα -iduronidase+++DS, HS
IIHunterIduronidase sulfatase++++++DS, HS
III † Sanfilippo AHeparan sulfatase+++++HS
Sanfilippo BN -acetylgluco-saminidase+++++HS
Sanfilippo CAcetyl CoA glucosamine acetyltransferase+++++HS
Sanfilippo DN -acetylglucosamine-6-sulfatase+++++HS
IVMorquio AGalactosamine-6-sulfatase++ / —+ / ++ / +++KS, chondroitin sulfate (CS)
Morquio Bβ -galactosidase++ / —+ / ++ / +++KS, CS
VNonexistent
VIMaroteaux-LamyN -acetylhexosamine-4-sulfatase++++DS
VIISly ‡ β -glucuronidase++++++DS, HS, CS
IXHyaluronidase deficiency § Hyaluronidase+Hyaluron
*Somatic features include organomegaly and facial coarsening.



† Eye findings may include cherry red spots.



‡ Severity widely varies; no neurologic degeneration is noted, but mental retardation is possible.



§ Only one patient has been described whose major features were periarticular soft tissue masses.



Table 2. Enzyme Replacement Therapy for the Mucopolysaccharidoses
MPS TypeDisease NameEnzyme DeficiencyERTCompanyClinical Use
IHurlerα -iduronidaselaronidase



(Aldurazyme)



GenzymeIn use
IH/SHurler-Scheieα -iduronidaselaronidaseGenzymeIn use
ISScheieα -iduronidaselaronidaseGenzymeIn use
IIHunterIduronidase sulfataseidursulfase



(Elaprase)



ShireIn use
III ‡ Sanfilippo AHeparan sulfatase.........
Sanfilippo BN- acetylglucosaminidase.........
Sanfilippo CAcetyl CoA glucosamine acetyltransferase.........
Sanfilippo DN -acetylglucosamine-6-sulfatase.........
IVMorquio AN-acetylgalactosamine-6-sulfataseelosulfase alfa (Vimizim)BioMarinIn use
Morquio Bβ -galactosidase.........
VIMaroteaux-LamyN -acetylhexosamine-4-sulfatasegalsulfase (Naglazyme)BioMarinIn use
VIISly § β -glucuronidase.........
IXHyaluronidase Deficiency || |Hyaluronidase.........
GSDIIPompeAcid α -glucosidasealglucosidase (Myozyme)GenzymeIn use
Note. This table represents the status of enzyme replacement therapy as of February 2014. Progress occurs on a daily basis; please investigate further for the most up to date information.
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