Most often, the parents of an individual with an autosomal recessive disorder are heterozygous carriers, having only one copy of the altered gene, without having signs and symptoms of the disorder.In about one-third of cases of hyperprolinemia, individuals carrying one copy of an altered PRODH gene have moderately elevated levels of proline in their blood, but these levels do not cause any health problems. Individuals with one altered ALDH4A1 gene have normal levels of proline in their blood. Diagnosis
Types
Hyperprolinemia type I
It is difficult to determine the prevalence of hyperprolinemia type I, as many people with the condition are asymptomatic. People with hyperprolinemia type I have proline levels in their blood between 3 and 10 times the normal level. Some individuals with type I exhibit seizures, intellectual disability, or other neurological problems. Hyperprolinemia type II
Hyperprolinemia type II results in proline levels in the blood between 10 and 15 times higher than normal, and high levels of a related compound called pyrroline-5-carboxylate. This rare form of the disorder may appear benign at times, but often involves seizures, convulsions, and intellectual disability.Hyperprolinemia can also occur with other conditions, such as malnutrition or liver disease. In particular, individuals with conditions that cause elevated levels of lactic acid in the blood, such as lactic acidemia, are likely to have elevated proline levels, because lactic acid inhibits the breakdown of proline. Treatment
Dietary restriction of protein intake. Research
A 2005 study on rats suggested that hyperprolininemia causes cognitive dysfunction.
Singing
Children are able to sing in the same octave as women. When the voices of male teenagers break, they are no longer able to sing in the same octave. For music sung in the same key as women, they can sing in falsetto or drop an octave. See also
Puberty
Voice masculinization and feminization


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