Other Genetic Disorder

Fragile X

Introduction

In about 25% male children with mental retardation (MR), the causes are mostly due to defects on the X chromosome. Some X-linked disorders include: Fragile X syndrome, Rett’s syndrome, Coffin-Lowry syndrome, Renpenning syndrome etc. Fragile X syndrome is the most common cause of dominantly inherited mental retardation (MR). It is caused by an expansion of a small part of the FMR1 gene located on the X chromosome. Parents should look out for the following symptoms for fragile X syndrome:

Symptoms to look out for

  • Did my child sit, walk and speak later than usual?
  • Does my child have large ears, prominent mandible and large testes?
  • Does my child have repetitive behaviour?
  • Is my child hyperactive with very short attention span?
  • Does my child keep flapping his/ her hands?
  • Does my child have poor eye or social contact (Autism)?
  • Did my child suffer from seizures at any point of time?
  • Does he/ she have difficulties in school and lags behind other children?
Klippel-Feil

KFS or Klippel-Feil Syndrome is characterized by congenital musculo-skeletal deformities with multiple disability of body as well as brain in addition to multiple variations of body involvements. Some features may resemble many Psychological and/or Neurodevelopmental disabilities like CP. KFS comprises three characteristic deformities: a short neck, a low dorsal hairline, restricted neck mobility. It may be associated with variants of cerebral palsy, mental retardation, and a wide variety of other physical deformities.

It is the result of synostosis (joining) of several cervical (neck) vertebrae, which may or may not be deformed. Other associated abnormalities reported include those related to urological (urinary system), neurological (brain and spinal cord) , cardiopulmonary (heart and lung) and locomotor (bone and joints including muscles and tendons) deformities, which significantly increase the morbidity.

Cause

There is a hypothesis that KFS could be the result of an interruption of the early embryonic blood supply in the subclavian (shoulder) arteries, the vertebral (neck) arteries and/or their branches. It is supposed that the occlusions occur at specific locations in these vessels during or around the sixth week of embryologic development and produce predictable patterns of defects.

RETT Syndrome

Rett syndrome is a childhood neurodevelopmental disorder in which a genetic mutation causes a the inability or impaired ability of the body to perform purposeful hand movements and expressive language. Rett syndrome is characterized by normal development during the first few months of life, followed by a loss (regression) of language and motor skills. Some children with Rett syndrome might have delays in acquiring skills early on (soon after birth). Rett syndrome affects girls almost exclusively. It’s rare — only about one in 10,000 to 15,000 girls will develop the condition. Most children with Rett syndrome have a mutation in a particular gene on the X chromosome. Exactly what this gene does, or how its mutation leads to Rett syndrome, isn’t clear. It’s believed that the single gene may influence many other genes involved in development.

Children with Rett syndrome may exhibit autistic behaviors such as impaired social interaction, impaired communication and unusual, restricted or repetitive behaviors (also called “stereotyped” behaviors or stereotypies). Rett syndrome also causes problems with muscles and coordination. Walking becomes awkward as girls develop a jerky, stiff-legged gait and may also have uncoordinated breathing and seizures.