What is Mucolipidoses?
It is a group of metabolic diseases, also known as lysosomal storage diseases, all of which are inherited. There are four main types of Mucolipidosis diseases.
They affect the body’s renewal of material within cells. This in turn leads to a build-up of higher-than-normal levels of carbohydrates and lipids (fatty materials) in the cells. This then creates damage to the cells and triggers the symptoms related to mucolipidosis syndromes.
In some affected individuals the symptoms are present at birth, in early childhood or eventually during adolescence. The main symptoms, including intellectual disability, are progressive and may worsen with time.
What gene changes cause Mucolipidoses?
A genetic defect is responsible for causing the syndrome. The genes responsible include GNPTAB, GNPTAG, and MCOLN1. Affected individuals are born with an inability to produce enough enzymes to break down carbohydrates and lipids.
These rare diseases are inherited in an autosomal recessive pattern. Autosomal recessive inheritance means an affected individual receives one copy of a mutated gene from each of their parents, giving them two copies of a mutated gene. Parents, who carry only one copy of the gene mutation will not generally show any symptoms but have a 25% chance of passing the copies of the gene mutations onto each of their children.
What are the main symptoms of Mucolipidoses?
The symptoms vary according to the type of Mucolipidosis an individual has.
- Mucolipidosis type I (ML I): swelling over the whole body usually present at birth, large tongue, flat nasal bridge, and enlarged gums. Other symptoms include skeletal abnormalities, seizures, tremors, failure to thrive, and respiratory infections. Life expectancy is rarely beyond one year.
- Mucolipidosis type II: symptoms of type II of the disease are often severe. They include coarse facial features, skeletal abnormalities, enlarged liver and spleen, short-trunk dwarfis,m and recurrent respiratory infections. Life expectancy with this type is generally below 7 years.
- Mucolipidosis type III: includes skeletal abnormalities, coarse facial features, and closing of the corneas. This is the most mild form of the disease and affected individuals generally have normal intellectual ability. Life expectancy reaches into adulthood.
- Mucolipidosis type IV (ML IV): main symptoms include gross motor delay, most affected individuals are not able to walk independently. Impaired vision is another major symptom. In some cases affected individuals may have even milder symptoms.
Possible clinical traits/features:
Incoordination, Cognitive impairment, Opacification of the corneal stroma, Gait disturbance, Genu recurvatum, Hyperreflexia, Microcephaly, Strabismus, Spastic tetraplegia, Infantile onset, Progressive retinal degeneration, Retinopathy, Palmoplantar keratoderma, Photophobia, Optic atrophy, Nystagmus, Autosomal recessive inheritance, Dystonia, Dysplastic corpus callosum, EEG abnormality, Everted lower lip vermilion, Decreased light- and dark-adapted electroretinogram amplitude, Coarse facial features, Developmental stagnation, Neurological speech impairment, Narrow forehead, Intellectual disability, Muscular hypotonia, Microdontia, Abnormal nasal morphology, Ganglioside accumulation, Abnormal electroretinogram, Abnormality of mucopolysaccharide metabolism, Abnormality of abdomen morphology, Abnormality of retinal pigmentation, Cerebellar atrophy, Cerebral dysmyelination, Aplasia/Hypoplasia of the abdominal wall musculature, Absent speech, Babinski sign.
How does someone get tested?
To find out if someone has a diagnosis of Mucolipidoses, it is important to have a consultation and evaluation with a clinical genetic specialist. Specialists may also suggest specific genetic testing or other types of tests to help reach a diagnosis. FDNA’s AI technology can help speed up the diagnostic process by analyzing facial features and other health information.
