MENDELIAN DISEASES

1
MENDELIAN DISEASES

• VINEETHA G GOPAL

2
INTRODUCTION

• Genetic Disorders
• Chromosomal
  Abnormalities
• Mendelian diseases
• Multifactorial diseases

3
MENDELIAN DISEASES

• Definition Diseases in which the phenotypes are
  largely determined by the action, lack of action,
  of mutations at individual loci.
• Rare 1 of all live born individuals
• 4 types of inheritance
• Autosomal dominant
• Autosomal recessive
• X linked dominant
• X linked recessive

4
(No Transcript)
5

• Offspring has a 5050 chance of being affected
• Both sexes equally affected
• Examples
• ABO Blood Group System
• Retinoblastoma
• Neurofibromatosis
• Marfans syndrome
• Familial polyposis coli

6
(No Transcript)
7

• Probability 25 (14)
• Both sexes equally affected
• Examples
• Hemoglobinopathies sickle cell
  anaemia,thalassemia
• Inborn errors of metabolismPKU,Alkaptonur
  ia
• Albinism
• Cystic Fibrosis
• Hirschsprung disease

8
(No Transcript)
9

• A mutant gene on X chromosome in males will
  express itself readily as there is no normal
  allele, but a mutant gene on X chromosome of
  females will not express itself in the presence
  of a normal allele
• Examples
• Hemophilia
• Colour blindness
• Duchenne muscular dystrophy
• G6PD deficiency

10
(No Transcript)
11

• Daughters are affected, sons escape
• Examples
• Vitamin D resistant Rickets
• Familial hypophosphatemia
• Blood group Xg

12
BLOOD GROUP SYSTEMS

• ABO System
• Gastric and duodenal ulcer Group O
• Stomach cancer Group A
• Rhesus system
• Erythroblastosis foetalis

13
(No Transcript)
14
SICKLE CELL ANAEMIA

• Prevalent in blacks specially in certain parts of
  Africa
• Heterozygous apparently healthy
• Homozygous severely anaemic and die before
  puberty
• Clinical features
• No specific treatment
• Prenatal diagnosis and prevention

15
THALASSEMIA

• Reduction in globin chain synthesis(alpha or
  beta)
• Clinical features-anaemia,marked
  hepatosplenomegaly and thalassemia facies
• Prenatal diagnosis and prevention

16
HAEMOPHILIA

• 15-20 of every 100,000 males
• Deficiency of clotting factor VIII
• Progressive joint disease and muscular atrophy
• Cause of death adverse effects of Rx-AIDS and
  other infections, liver disease secondary to
  hepatitis

17
CYSTIC FIBROSIS

• Common in European population(1 in 2000 births)
• Affects respiratory and gastrointestinal tracts
  and sweat glands
• Viscid mucous secretions-cause obstruction of
  airways, bile canaliculi
• Life expectancy now more than 30 yrs

18
PHENYLKETONURIA

• Deficiency of phenyl alanine hydroxylase
• Accumulation of phenyl alanine in blood and
  tissues esp brain leading to mental retardation
• Diagnosis by detecting raised blood levels of
  phenyl alanine
• Treatmentdiet low in phenyl alanine

19
PREVENTION AND CONTROL

• General health promotion
• Specific protection
• Early diagnosis and Rx
• Detection of carriers
• Prenatal diagnosis
• Neonatal screening
• Recognizing preclinical cases
• Rehabilitation

20

• THANK YOU