Muscular Dystrophy : Muscular Dystrophy Mrs. Rani Ashok
Assistant Professor in Zoology
Lady Doak College, Madurai - 2 Definition : Definition Muscular dystrophy is a group of disorders recognized by progressive muscle weakness and loss of muscle tissue. Who Discovered Muscular Dystrophy : Who Discovered Muscular Dystrophy Each neuromuscular disease (muscular dystrophy) was discovered by different person. 43 Different Types of Neuromuscular Diseases … : 43 Different Types of Neuromuscular Diseases … Ataxia
Congenital Myasthenic syndrome
Emery-Dreifus muscular dystrophy Limb girdle
Myotonia Congenita (Thomsen's and Becker's disease)
Oculopharyngeal muscular dystrophy Causes : Causes Inheritance
Depends on the age when symptoms appear, and the types of symptoms that develop. Basic Symptoms : Basic Symptoms Muscle weakness
Delayed development of muscle skills
Difficulty using a muscle group (specific muscle depends on the type of MD)
Eyelid drooping Basic Symptoms : Basic Symptoms Muscle deformities
Contracture deformities (clubfoot, claw hand or others)
Enlargement of the calve muscles (pseudohypertrophy) Symptoms : Symptoms Symptoms vary with the different types of muscular dystrophy. Certain types, such as Duchnne dystrophy, are ultimately fatal while other types have associated muscle weakness but cause little disability. Symptoms : Symptoms Intellectual retardation
Only present in some types of Muscular Dystrophy
Skeletal deformities Risks : Risks Because these are inherited disorders, risk include a family history of muscular dystrophy. Where is This Gene? : Where is This Gene? Clinical FeaturesGenotype of DMD : Clinical FeaturesGenotype of DMD Females carry the DMD gene on the X chromosome.
Females are carriers and have a 50% chance of transmitting the disease in each pregnancy.
Sons who inherit the mutation will have the disease.
Daughters that inherit the mutation will be carriers.
The DMD gene is located on the Xp 21 band of the X chromosome.
Mutations which affect the DMD gene.
96% are frameshift mutations
30% are new mutations
10-20% of new mutations occur in the gametocyte (sex cell, will be pass on to the next generation).
The most common mutation are repeats of the CAG nucleotides. Genotype of DMD (Cont.) : Genotype of DMD (Cont.) During the translocation process, a mutation occurs.
Mutations leading to the absence of dystrophin
Very Large Deletions (lead to absence of dystrophin)
Mutations causing reading errors (causes a degraded, low functioning DMD protein molecule)
Point Mutations Slide 14: The Lancet NeurologyVolume 2 • Number 5 • May 2003Copyright © 2003 Elsevier 3D Images of The Actin Binding Sight Of Dystrophin : 3D Images of The Actin Binding Sight Of Dystrophin Prevalence : Prevalence Types may be more prevalent in some cultures.
Both sexes tend to be affected equally, depending upon the type.
Many muscular dystrophies occur in childhood, others occur as late as 60 years of age. How Many People Are Affected by Muscular Disease : How Many People Are Affected by Muscular Disease It is estimated that between 50,000 -250,000 are affected annually. This number seems to be growing each year due to advanced technology and earlier testing. Allelic Variants : Allelic Variants Slide 19: Thank You