Mucolipidosis Type IV (ML4)
· What is
Mucolipidosis Type IV (ML4)?
· Symptoms of ML4
· How Do I
Know if My Child Has ML4?
· Diagnosis
· Treatment
· Incidence
in People of Jewish Descent
· Testing
· How Can My Child
Be Tested?
· Resources
and More
Mucolipidosis type IV (ML4), first described in 1974, is the most recently
recognized Jewish genetic disease. To date, over 70 patients, most of
Ashkenazic Jewish descent, have been reported.
Mucolipidosis Type IV is an autosomal recessive disorder, mainly seen in Jews of Eastern European background. It is a cation channel disorder that is characterized by severe neurological and ophthalmologic abnormalities. ML4 usually presents during the first year of life with mental retardation, corneal opacities, and delayed motor milestones. Children with ML4 typically reach a maximum developmental age of 15 months in language and motor function, although their receptive abilities are more advanced. Children diagnosed with ML4 experience retinal degeneration that severely limits their vision. There is currently no treatment for this tragic disorder.
Children with ML4 begin to exhibit developmental delay during the first year of life. Many parents seek ophthalmologic evaluations for pseudo-strabismus. Motor and mental retardation ranges from mild to severe. The earliest sign is corneal clouding; however, approximately 30% of patients develop clouding between three and five years of age. Other eye findings may include pseudostrabismus (false appearance of crossed eyes) and/or retinal degeneration, which may lead to blindness in later years. There is no gross involvement of the skeletal system nor urinary mucopolysaccharide excretion. Patients currently range from one to 45 years of age. Prognosis and life expectancy beyond the latter age is unknown. Recently, a few very mildly affected children with ML4 have been diagnosed. This raises the possibility of other undiagnosed mildly involved patients.
How do I know if my child has ML4?
The only way to know if your child has ML4 is to have your child examined
and tested by a doctor.
As a parent, you can observe whether your child has
the following symptoms commonly associated with ML4 and generally appearing
in the first year:
· Pronounced developmental delays in gross motor skills, such as sitting,
standing and walking;
· Pronounced developmental delays in fine motor skills, such as holding a
cup or crayon;
· Pronounced developmental delays in speech;
· Vision problems of corneal clouding, retinal degeneration, sensitivity to
light, and strabismus; and,
· Low muscle tone (hypotonia).
If you observe these symptoms, tell you child’s doctor.
Diagnosis
The name, ML4, derives from the presence of diagnostic storage bodies (cytoplasmic inclusions seen under electron microscope) in almost every cell of these patients. The storage bodies are similar to those observed in the mucopolysaccharide and lipid storage diseases; thus the designation mucolipidosis. The diagnosis should be considered in retarded Jewish children who have corneal clouding. The electron microscopic demonstration of characteristic storage bodies in a conjunctival biopsy supports the clinical diagnosis. .
Treatment
At present, no specific therapy is available. Optimal supportive care,
including physical, occupational and speech therapy, can significantly improve
the function and quality of life of affected children. Families with affected
children should seek genetic counseling and be offered the option of prenatal
diagnosis for future pregnancies.
Incidence in People of Jewish
Descent
One in 100 Ashkenazi Jews is a carrier.
Testing
There is a carrier screening test
which requires a sample of blood that can determine whether or not there is a gene
mutation present for Mucolipidosis Type IV
Prenatal diagnosis for ML4 can be attained with the use of CVS (Chorionic
Villus Sampling) or Amniocentesis, which are performed early in the pregnancy.
There is now a simple blood test to diagnose ML4. The blood test will also detect very low gastrin (stomach acid) levels which are common in children with ML4.
Resources and More
Randy Yudenfriend
President, ML4 Foundation
MUCOLIPIDOSIS IV FOUNDATION
719 East 17th Street
Brooklyn, New York 11230
718-434-5067
Email:
www@ml4.org
Website:
http://www.ml4.org