Kidney and heart tissues were found to not have a COX deficiency.French Canadian Leigh syndrome has similar symptoms to other types of Leigh syndrome. The age of onset is, on average, 5 months and the median age of death is 1 year and 7 months. Children with the disease are developmentally delayed, have mildly dysmorphic facial features, including hypoplasia of the midface and wide nasal bridge, chronic metabolic acidosis, and hypotonia (decreased muscular strength). Other symptoms include tachypnea (unusually quick breathing rate), poor sucking ability, hypoglycemia (low blood sugar), and tremors. Severe, sudden metabolic acidosis is a common cause of mortality.Estimates of the rate of genetic carriers in the Saguenay-Lac-Saint-Jean region range from 1 in 23 to 1 in 28; the number of children born with the disease has been estimated at 1 in 2063 to 1 in 2473 live births. Genealogic studies suggest that the responsible mutation was introduced to the region by early European settlers. Pathophysiology
The characteristic symptoms of Leigh syndrome are at least partially caused by bilateral, focal lesions in the brainstem, basal ganglia, cerebellum, and other regions of the brain. The lesions take on different forms, including areas of demyelination, spongiosis, gliosis, necrosis, and capillary proliferation. Demyelination is the loss of the myelin sheath around the axons of neurons, inhibiting their ability to communicate with other neurons. The brain stem is involved in maintaining basic life functions such as breathing, swallowing, and circulation; the basal ganglia and cerebellum control movement and balance.
(SOURCE 1) In more recent scientific literature, there is evidence in which pedigree analyses confirm autosomal dominant, autosomal recessive or even as X-linked inherited cases of the HGF trait.In 2002, researchers described the SOS1 gene and proved for the first time that a single-nucleotide–insertion mutation of the SOS1 gene on codon 1083 is the preliminary cause of HGF1 in humans. (Source 1) Later on in 2010, there was a case study done on a 16-year-old male with severe gingival overgrowth, almost covering all teeth. Researchers approached this issue with periodontics - a partial gingivectomy and flap surgery. This case study concluded that surgery followed by regular follow-ups is a good way to treat HGF despite the fact that the risks of re-occurrence of the condition remain high.Even more recently, a study was done in 2013 on a family that showed history of autosomal recessive inheritance of HGF. The study did not dismiss the return of HGF after treatment but did claim that general surgical intervention after scaling and root planning of teeth supplemented with good oral hygiene is good enough to prevent the re-occurrence of HGF. This case study also acknowledged how HGF can be part of a multi-system syndrome associated with disorders such as Zimmermann Laband syndrome (ear, nose, bone, and nail defects with hepatosplenomegaly), Rutherford syndrome  (microphthalmia, mental retardation, athetosis, and hypopigmentation), Murray-Puretic Drescher syndrome and Ramon syndrome. See also
Chronic periodontitis
Epidemiology of periodontal diseases
Gingivitis
Gum graft
Periodontist
Tooth loss
Gingival recession

References
External links

American Academy of Periodontology Home Page
Periodontal Disease as a Specific, albeit Chronic, Infection: Diagnosis and Treatment