Information on the following diseases can be found in the Related Disorders section of this report:

• Bardet-Biedl Syndrome
• Prader-Willi Syndrome
• Borjeson Syndrome
• Hypogonadotrophic Hypogonadism
• Alstrom Syndrome
• Weiss Syndrome
• Biemond II

The symptoms of Laurence-Moon Syndrome usually occur in early or late childhood. Visual difficulties may include crossed eyes (strabismus), night blindness, or the progressive loss of vision caused by changes in the lens of the eyes (cataracts). Affected children may also have abnormally small eyes. The progressive degeneration of the retina of the eyes (retinitis pigmentosa) typically occurs during childhood. (For more information on this disorder, choose "Retinitis Pigmentosa" as your search term in the Rare Disease Database.)

Decreased levels of hormone production by the testes or ovaries (hypogonadism) usually cause a delay in the onset of puberty and the development of secondary sex characteristics (i.e., facial and pubic hair) in children with Laurence-Moon Syndrome. Males are usually infertile and may develop breast-like tissue (pseudogynecomastia). Females may not have regular menstrual periods (amenorrhea) and fail to develop breasts.

The other signs of Laurence-Moon Syndrome include mental retardation, an awkward gait (ataxia), muscle rigidity, and paralysis of the legs and lower part of the body accompanied by involuntary muscle contractions (spastic paraplegia).

Kidney disease is common in people with Laurence-Moon Syndrome, because of abnormalities in the structure or function of the kidneys. In some rare cases diabetes, congenital heart defects, and breathing problems may also occur.

Laurence-Moon Syndrome is thought to be inherited as an autosomal recessive genetic trait that may involve one or two genes on the same chromosome. Human traits, including the classic genetic diseases, are the product of the interaction of two genes, one received from the father and one from the mother. In recessive disorders, the condition does not appear unless a person inherits the same defective gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk of transmitting the disease to the children of a couple, both of whom are carriers for a recessive disorder, is 25 percent. Fifty percent of their children risk being carriers of the disease, but generally will not show symptoms of the disorder. Twenty-five percent of their children may receive both normal genes, one from each parent, and will be genetically normal (for that particular trait). The risk is the same for each pregnancy.

It is thought that Laurence-Moon Syndrome is inherited by the transmission of 2 recessive genes on the same chromosome.

Laurence-Moon Syndrome is a rare disorder that affects twice as many males as females. Approximately 600 cases have been reported in the medical literature. This syndrome seems to occur with greater frequency among Arab populations from Kuwait.

Symptoms of the following disorders can be similar to those of Laurence-Moon Syndrome. Comparisons may be useful for a differential diagnosis:

Bardet-Biedl Syndrome is a rare disorder affecting many systems in the body. It is inherited as an autosomal recessive genetic trait. The major symptoms of this disorder may include mental retardation, obesity, delayed sexual development, underdeveloped reproductive organs, degeneration of the retina of the eyes, kidney abnormalities, and/or abnormal fingers or toes. This disorder affects males and females in equal numbers.

Prader Willi Syndrome is a complex disorder affecting many systems in the body. It is diagnosed more often in males born after a prolonged, delayed birth in the breech position. It is characterized by muscular weakness and failure to thrive during infancy. There is a decrease in the function of the testes or ovaries (hypogonadism), short stature, and impaired intellectual capabilities in later childhood. Between 1 and 3 years of age, a need for an extraordinary amount of food (hyperphagia) usually develops. If left uncontrolled, obesity can lead to life-threatening heart and lung complications. (For more information on this disorder, choose "Prader Willi" as your search term in the Rare Disease Database.)

Borjeson Syndrome is a rare disorder thought to be inherited as an X- linked dominant genetic trait with less severe symptoms in females. Major characteristics of this disorder may include an unusual facial appearance, mental retardation, seizures, short stature, slowed sexual development, muscle weakness and/or obesity.

Hypogonadotropic hypogonadism (secondary hypogonadism) is a disorder that effects the development of the region of the hypothalamus that regulates the production of hormones which stimulate the ovaries or testes (gonadotropins). People with this disorder have reduced levels of hormone secretion, and experience a delay in the development or absence of secondary sexual characteristics.

Alstrom Syndrome is a rare inherited disorder characterized by progressive loss of vision (retinitis pigmentosa) and childhood obesity. Involuntary rhythmic movements of the eyes and the loss of central vision typically occur. Children with this disorder generally develop hearing loss and diabetes mellitus after the age of ten years. Alstrom Syndrome is similar to Laurence-Moon Syndrome, but without mental retardation or polydactyly. (For more information on this disorder, choose "Alstrom" as your search term in the Rare Disease Database.)

Weiss Syndrome is an extremely rare disorder characterized by hypogonadism, and mental retardation. Other characteristics include obesity and deafness.

Biemond II Syndrome is a rare inherited disorder characterized by obesity, hypogonadism, and extra fingers or toes (polydactyly). Progressive visual loss occurs due to abnormalities of the iris of the eyes.

In Laurence-Moon Syndrome, the testes do not seem to respond to the administration of sex hormones. Therefore, stimulation with gonadotrophic hormones does not seem to be a useful treatment. Visual aids may help those who have retained some useful vision. A strictly controlled diet may help manage appetite and control weight.

Researchers at the Cullen Eye Institute of the Baylor College of Medicine in Houston, Texas are studying inherited retinal diseases including Laurence-Moon Syndrome. Families with at least two affected members and both parents living are needed to participate in this program. Other disorders included in the study are Lowe's Syndrome, Leber's Congenital Amaurosis, Macular Degeneration and Polymorphic Macular Degeneration, Laurence-Moon Syndrome, Rod Monochromacy (Complete Congenital Achromatopsia), Blue Cone Monochromacy (Congenital Incomplete X-linked Achromatopsia), Choroidermia, and Hereditary X-linked cataracts. For more information on the diagnostic testing program, physicians can contact the Biochemical Genetics Laboratory at (800) 246-2436. Indigent individuals without medical insurance may contact:

Dr. Richard Lewis
Cullen Eye Institiute
Baylor College of Medicine
(713) 798-3030

Genetic counseling may be of benefit for affected individuals and their families. Other treatment is symptomatic and supportive.

Research on genetic defects and their causes is ongoing. The National Institutes of Health (NIH) is sponsoring the Human Genome Project which is aimed at mapping every gene in the human body and learning why they sometimes malfunction. It is hoped that this new knowledge will lead to prevention and treatment of genetic disorders in the future.

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