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What is Laurence–Moon syndrome and explain in detail?
Laurence–Moon syndrome (LMS) is a rare autosomal recessive genetic disorder associated with retinitis pigmentosa, spastic paraplegia, and mental disabilities.

Signs and symptoms
Intellectual disability, hexadactyly, central diabetes insipidus, blindness (usually by 30 years due to central retinal degeneration).

Genetics
LMS is inherited in an autosomal recessive manner. This means the defective gene responsible for the disorder is located on an autosome, and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder.

Diagnosis
The syndrome was originally thought to have five cardinal features (and recently a sixth was added), on the basis of which a diagnostic criterion was developed:
4 primary features or 3 primary features and 2 secondary features must be present.
The primary features are:
1. Polydactyly
2. Rod-cone dystrophy
3. Learning disabilities
4. Obesity
5. Hypogonadism in males
6. Renal abnormalities
While the secondary features are stated to be as:
1. Speech disorder and/or developmental delay
2. Ophthalmic abnormalities other than rod-cone dystrophy (strabismus, cataract, astigmatism etc.)
3. Brachydactyly or Syndactyly
4. Polyuria and/or polydipsia (nephrogenic diabetes insipidus)
5. Ataxia, poor coordination, imbalance
6. Mild spasticity (especially lower limbs)
7. Diabetes mellitus
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