Diagnosis
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| MEDNIK syndrome | |
|---|---|
| Other names | Intellectual disability-enteropathy-deafness-peripheral neuropathy-ichthyosis-keratodermia syndrome |
MEDNIK syndrome (OMIM#609313), [1] also known as "syndrome de Kamouraska" (syndrome from Kamouraska), is a genetic disorder that is caused by mutations to the AP1S1 gene. Transmission of the disease is believed to be autosomal recessive. Symptoms of the syndrome are intellectual disability, enteropathy, deafness, neuropathy, ichthyosis, and keratoderma (MEDNIK). [2] [3] People with MEDNIK syndrome often have a high forehead, upslanting palpebral fissures, a depressed nasal bridge, low-set ears, growth retardation, and brain atrophy apparent upon imaging. [4] The disorder was discovered by Patrick Cossette and his research team from the Université de Montréal. MEDNIK syndrome was initially reported in a few French-Canadian families near Quebec who all shared common ancestors. [2]
MEDNIK syndrome has been shown to create a defect in copper metabolism. Before MEDNIK, the only two inherited copper metabolism disorders known were Menkes disease and Wilson's disease. [2] Menkes and Wilson's disease are both caused by mutations in copper ATPases that are distinct for each disease. Both ATPases, ATP7A (Menkes) and ATP7B (Wilson's) are located in the trans-Golgi network and are responsible for transporting copper to cuproenzymes synthesized within the secretory compartments. [2] Patients with MEDNIK syndrome have been shown to display combined clinical and biochemical signs of both Menkes and Wilson's diseases. [2]
The transport of copper, recycling of copper ATPases, and copper detoxification are reliant on proper intracellular copper trafficking. The defect in the AP1S1 gene causes improper function and trafficking of copper ATPases resulting in less retention in the trans-Golgi and excess copper in the plasma membrane.
The mutation that causes the MEDNIK syndrome occurs in the gene, AP1S1, which codes for the smallest subunit of the AP1 adaptor complex. [3] The AP-1 complex is one of five Adaptor Protein complexes that are found in eukaryotic cells. AP complexes mediate trafficking linking clathrin or other coat proteins to receptors in coated vesicles, selectively sorting cargo between cell membrane, trans-Golgi network, and endosomal compartments. The AP-1 complex is found in the trans-Golgi network and is responsible for controlling AP-1-coated vesicles and the trafficking of the ATPase's ATP7A and ATP7B. A mutation in AP1S1 causes abnormal intracellular copper trafficking which subsequently affects copper-dependent enzymes leading to the symptoms of MEDNIK disease. [3]
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There is currently no cure or treatments tailored directly toward MEDNIK syndrome. [2] [3] However, symptoms can be treated on an individual basis. Treatments can include: diuretics, steroids, pain medications, antidepressants, hydrotherapy, anti-inflammatories, and antibiotics. [5]
Wilson's disease is a genetic disorder characterized by the excess build-up of copper in the body. Symptoms are typically related to the brain and liver. Liver-related symptoms include vomiting, weakness, fluid build-up in the abdomen, swelling of the legs, yellowish skin, and itchiness. Brain-related symptoms include tremors, muscle stiffness, trouble in speaking, personality changes, anxiety, and psychosis.
A congenital disorder of glycosylation is one of several rare inborn errors of metabolism in which glycosylation of a variety of tissue proteins and/or lipids is deficient or defective. Congenital disorders of glycosylation are sometimes known as CDG syndromes. They often cause serious, sometimes fatal, malfunction of several different organ systems in affected infants. The most common sub-type is PMM2-CDG where the genetic defect leads to the loss of phosphomannomutase 2 (PMM2), the enzyme responsible for the conversion of mannose-6-phosphate into mannose-1-phosphate.
Occipital horn syndrome (OHS), formerly considered a variant of Ehlers–Danlos syndrome, is an X-linked recessive mitochondrial and connective tissue disorder. It is caused by a deficiency in the transport of the essential mineral copper, associated with mutations in the ATP7A gene.
Chylomicrons, also known as ultra low-density lipoproteins (ULDL), are lipoprotein particles that consist of triglycerides (85–92%), phospholipids (6–12%), cholesterol (1–3%), and proteins (1–2%). They transport dietary lipids, such as fats and cholesterol, from the intestines to other locations in the body, within the water-based solution of the bloodstream. ULDLs are one of the five major groups lipoproteins are divided into based on their density. A protein specific to chylomicrons is ApoB48.
Ceruloplasmin is a ferroxidase enzyme that in humans is encoded by the CP gene.
Menkes disease (MNK), also known as Menkes syndrome, is an X-linked recessive disorder caused by mutations in genes coding for the copper-transport protein ATP7A, leading to copper deficiency. Characteristic findings include kinky hair, growth failure, and nervous system deterioration. Like all X-linked recessive conditions, Menkes disease is more common in males than in females. The disorder was first described by John Hans Menkes in 1962.
ICF syndrome is a very rare autosomal recessive immune disorder.
Mitochondrial myopathies are types of myopathies associated with mitochondrial disease. Adenosine triphosphate (ATP), the chemical used to provide energy for the cell, cannot be produced sufficiently by oxidative phosphorylation when the mitochondrion is either damaged or missing necessary enzymes or transport proteins. With ATP production deficient in mitochondria, there is an over-reliance on anaerobic glycolysis which leads to lactic acidosis either at rest or exercise-induced.
ATP7A, also known as Menkes' protein (MNK), is a copper-transporting P-type ATPase which uses the energy arising from ATP hydrolysis to transport Cu(I) across cell membranes. The ATP7A protein is a transmembrane protein and is expressed in the intestine and all tissues except liver. In the intestine, ATP7A regulates Cu(I) absorption in the human body by transporting Cu(I) from the small intestine into the blood. In other tissues, ATP7A shuttles between the Golgi apparatus and the cell membrane to maintain proper Cu(I) concentrations in the cell and provides certain enzymes with Cu(I). The X-linked, inherited, lethal genetic disorder of the ATP7A gene causes Menkes disease, a copper deficiency resulting in early childhood death.
2-Methylbutyryl-CoA dehydrogenase deficiency is an autosomal recessive metabolic disorder. It causes the body to be unable to process the amino acid isoleucine properly. Initial case reports identified individuals with developmental delay and epilepsy, however most cases identified through newborn screening have been asymptomatic.
Vesicular transport adaptor proteins are proteins involved in forming complexes that function in the trafficking of molecules from one subcellular location to another. These complexes concentrate the correct cargo molecules in vesicles that bud or extrude off of one organelle and travel to another location, where the cargo is delivered. While some of the details of how these adaptor proteins achieve their trafficking specificity has been worked out, there is still much to be learned.
Protein losing enteropathy (PLE) is a syndrome in which blood proteins are lost excessively via the gastrointestinal (GI) tract. It may be caused by many different underlying diseases that damage the lining of the GI tract (mucosa) or cause blockage of its lymphatic drainage.
RAPADILINO syndrome is an autosomal recessive disorder characterized by:
Vici syndrome, also called immunodeficiency with cleft lip/palate, cataract, hypopigmentation and absent corpus callosum, is a rare autosomal recessive congenital disorder characterized by albinism, agenesis of the corpus callosum, cataracts, cardiomyopathy, severe psychomotor retardation, seizures, immunodeficiency and recurrent severe infections. To date, about 50 cases have been reported.
ATOX1 is a copper metallochaperone protein that is encoded by the ATOX1 gene in humans. In mammals, ATOX1 plays a key role in copper homeostasis as it delivers copper from the cytosol to transporters ATP7A and ATP7B. Homologous proteins are found in a wide variety of eukaryotes, including Saccharomyces cerevisiae as ATX1, and all contain a conserved metal binding domain.
Wrinkly skin syndrome(WSS) is a rare genetic condition characterized by sagging, wrinkled skin, low skin elasticity, and delayed fontanelle (soft spot) closure, along with a range of other symptoms. The disorder exhibits an autosomal recessive inheritance pattern with mutations in the ATP6V0A2 gene, leading to abnormal glycosylation events. There are only about 30 known cases of WSS as of 2010. Given its rarity and symptom overlap with other dermatological conditions, reaching an accurate diagnosis is difficult and requires specialized dermatological testing. Limited treatment options are available but long-term prognosis is variable from patient to patient, based on individual case studies. Some skin symptoms recede with increasing age, while progressive neurological advancement of the disorder causes seizures and mental deterioration later in life for some patients.
Copper is an essential trace element that is vital to the health of all living things. In humans, copper is essential to the proper functioning of organs and metabolic processes. Also, in humans, copper helps maintain the nervous system, immune system, brain development, and activates genes, as well as assisting in the production of connective tissues, blood vessels, and energy. The human body has complex homeostatic mechanisms which attempt to ensure a constant supply of available copper, while eliminating excess copper whenever this occurs. However, like all essential elements and nutrients, too much or too little nutritional ingestion of copper can result in a corresponding condition of copper excess or deficiency in the body, each of which has its own unique set of adverse health effects.
Wilson disease protein (WND), also known as ATP7B protein, is a copper-transporting P-type ATPase which is encoded by the ATP7B gene. The ATP7B protein is located in the trans-Golgi network of the liver and brain and balances the copper level in the body by excreting excess copper into bile and plasma. Genetic disorder of the ATP7B gene may cause Wilson's disease, a disease in which copper accumulates in tissues, leading to neurological or psychiatric issues and liver diseases.
LRBA deficiency is a rare genetic disorder of the immune system. This disorder is caused by a mutation in the gene LRBA. LRBA stands for “lipopolysaccharide (LPS)-responsive and beige-like anchor protein”. This condition is characterized by autoimmunity, lymphoproliferation, and immune deficiency. It was first described by Gabriela Lopez-Herrera from University College London in 2012. Investigators in the laboratory of Dr. Michael Lenardo at National Institute of Allergy and Infectious Diseases, the National Institutes of Health and Dr. Michael Jordan at Cincinnati Children’s Hospital Medical Center later described this condition and therapy in 2015.
Barakat-Perenthaler syndrome is a rare neurodevelopmental genetic disorder, presenting with a severe epileptic encephalopathy, developmental delay, Intellectual disability, progressive microcephaly and visual disturbance. It is listed by the standard reference, Online Mendelian Inheritance in Man (OMIM) as #618744. and classified as EPILEPTIC ENCEPHALOPATHY, EARLY INFANTILE, 83; EIEE83. It was first described in 2019 by Dr. Stefan Barakat and his team at the Erasmus University Medical Center in Rotterdam in the journal Acta Neuropathologica; the most recent reviews were published in Epilepsy Currents. and Trends in Endocrinology and Metabolism
Ref Syndrome de Kamouraska:, http://www.tvanouvelles.ca/2018/07/27/vivre-avec-le-syndrome-de-kamouraska (French)