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
8. Dental crowding, hypodontia, small roots, high arched palate
9. Congenital heart disease
10. Hepatic fibrosis

Treatment
There is no cure to LNMS. However, symptomatic treatment is often provided. The patients with LNMS often experience ataxia, spasticity and contractures, restricting their movements and daily activities.
Prognosis
Hereditary motor and sensory neuropathy are relatively common and are often inherited with other neuromuscular conditions, and these comorbidities cause an accelerated progression of the disease.Most forms of HMSN affect males earlier and more severely than females, but others show no predilection to either sex. HMSN affects all ethnic groups, with the most common forms having no racial predilection, but other recessively inherited forms tending to impact specific ethnic groups. Onset of HMSN is most common in early childhood, with clinical effects occurring before the age of 10, but some symptoms are lifelong and progress slowly. Therefore, these symptoms do not appear until later in life. See also
Hereditary motor and sensory neuropathy with proximal dominance
Charcot–Marie–Tooth disease
Hereditary motor neuropathies
Hereditary sensory and autonomic neuropathies
Spinal muscular atrophies

References
Further reading
Reilly MM (October 2000). "Classification of the hereditary motor and sensory neuropathies". Curr. Opin. Neurol. 13 (5): 561–4. doi:10.1097/00019052-200010000-00009. PMID 11073363. S2CID 43241647. == External links ==