Laurence–Moon syndrome

Overview

Laurence–Moon syndrome (LMS) is a rare, inherited neurodegenerative disorder characterized by a combination of vision loss, intellectual disability, movement abnormalities, and hormonal dysfunction. It was first described in the 19th century by Drs. Laurence and Moon. Historically, it was grouped with Bardet–Biedl syndrome due to overlapping features, but it is now recognized as a distinct condition. LMS affects multiple organ systems and typically manifests in early childhood, with progressive symptoms over time.

Causes

Laurence–Moon syndrome is caused by genetic mutations that are typically inherited in an autosomal recessive manner. This means a child must inherit two copies of the faulty gene—one from each parent—to develop the condition. While the exact genes involved in LMS are still being studied, some overlap with the genes implicated in Bardet–Biedl syndrome has been noted. The mutations result in cellular dysfunction, especially in ciliated cells, affecting sensory perception and hormonal signaling.

Symptoms

The clinical presentation of LMS is variable, but hallmark features usually include:

• Progressive vision loss – due to retinitis pigmentosa, typically presenting in childhood and leading to blindness

• Intellectual disability – ranging from mild to moderate cognitive impairment

• Spastic paraplegia – increased muscle tone and weakness in the lower limbs, leading to gait difficulties

• Hypogonadism – underdevelopment of sexual organs and delayed or absent puberty

• Obesity – particularly during adolescence and adulthood (less prominent than in Bardet–Biedl syndrome)

• Speech and developmental delays

Unlike Bardet–Biedl syndrome, LMS typically lacks features such as polydactyly (extra fingers or toes) and renal abnormalities.

Diagnosis

Diagnosis of Laurence–Moon syndrome is based on a combination of clinical features, family history, and genetic testing. Diagnostic approaches include:

• Ophthalmologic examination – to detect retinitis pigmentosa and visual field defects

• Neurological evaluation – to assess spasticity, reflexes, and motor function

• Endocrine testing – to evaluate hormone levels related to gonadal and pituitary function

• MRI or CT scans – may be used to detect brain or spinal cord abnormalities

• Genetic testing – to identify causative mutations and confirm the diagnosis

Treatment

There is no cure for Laurence–Moon syndrome, and treatment focuses on symptom management and improving quality of life. A multidisciplinary approach is essential and may include:

• Vision support – including low vision aids, orientation and mobility training, and educational resources for the visually impaired

• Physical therapy – to address spasticity and improve mobility and strength

• Hormone replacement therapy – for individuals with hypogonadism or other endocrine dysfunctions

• Special education services – for cognitive and developmental support

• Nutritional counseling – to manage weight and support healthy development

• Regular monitoring – by neurologists, endocrinologists, and ophthalmologists

Prognosis

The prognosis for individuals with Laurence–Moon syndrome varies depending on the severity of symptoms and the availability of supportive care. While the condition is progressive, early intervention can improve functional outcomes and quality of life. Most individuals will experience significant vision impairment and motor disability, but many can achieve a degree of independence with the right support systems. Life expectancy may be slightly reduced due to complications related to mobility, vision loss, or hormonal imbalance, but proper management can mitigate many of these risks.