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What are the 9 Abnormalities of Development?

Mar 27, 2023

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Abnormalities of Development (3 ‘D’ S)

Developmental Delay

Developmental Dissociation

Developmental Deviancy

Developmental Red Flags

Important causes of Development delay (“CDGP PIC”)

Developmental Assessment

Developmental quotient [D.Q.]

Screening Tests for Developmental Assessments

Definitive Tests for Intellectual & Developmental Assessment

Intelligence Quotient (IQ)

Intellectual Disability

What are the 9 Abnormalities of Development?

All babies achieve some fundamental milestones during the first few months of their development. If these milestones are not achieved, then it hints to some underlying development abnormality. Read this blog post to understand all the 9 types of development abnormalities.

Development and abnormalities related to it are an important and indispensable part of Pediatrics


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Abnormalities of Development (3 ‘D’ S)

  1. Delay
  2. Dissociation
  3. Deviancy 

Developmental Delay

  • When child’s performance in 1 or more domains is significantly below average or what is expected.

Developmental Dissociation

  • Substantial difference in the rate of development of milestones in 2 or more domains
  • Example: Isolated speech delay is a developmental dissociation since only language is hampered while all other domains are normal.

Developmental Deviancy

  • Developmental milestones occurring out of sequence.
  • Example: If Crawling comes before sitting.

Developmental Red Flags

  • The upper time limit by which the milestones should usually be attained.
Gross motorUpper limitUsual time
Sitting with support9 months6 months
Standing with support12 months9 months 
Walking with support15 months12 months 
Fine motorUpper limitUsual time
Pincer graspmonths12 months9 months
Scribbling24 months15 months
SocialUpper limitUsual time
Social Smile6 months   2-3 months
Waving bye-bye12 months   9 months
LanguageUpper limitUsual time
Babbling12 months6 months 
Single words15-16 months1 year
  • If these milestones are not attained by this time, then there is probably some underlying abnormality of development.

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Important causes of Development delay (“CDGP PIC”)

  1. C - Chromosomal abnormalities (Trisomy 21, 13, 18)
  2. D -Developmental brain abnormalities (lissencephaly- brain appears smooth due to less gyri & sulci, myelomeningocele)
  3. G - Genetic syndromes (Fragile X Syndrome, Rett syndrome, Prader Willi syndrome Nooram syndrome)
  4. P - Perinatal factors: Asphyxia, HIE (Hypoxic Ischemic Encephalopathy)
  5. P - Postnatal factors and acquired: (CNS Trauma, infections, Hypothyroidism,  malnutrition)
  6. I - Inborn errors of Metabolism: Maple Syrup Urine Disease, organic Acidemia, Tay sachs disease, GM Gangliosidosis, Mucopolysaccharidosis
  7. C - Congenital infections: TORCH group (Toxoplasmosis, Other agents, Rubella, CMV, Herpes)

Developmental Assessment

Developmental quotient [D.Q.]

  • D.Q = Developmental age/Chronological age x 100
  • E.g. A child of 6 years of age has attained milestones of that of a 3 year old only. Calculate D.Q.  

Solution: DQ = 3yr/ 6yr x 100 = 50

Screening Tests for Developmental Assessments

  1. P - Phatak’s Baroda Screening Tests
  2. A - Ages & stages questionaire
  3. R - Revised DDST (Denver Developmental Screening Test)
  4. T - Trivandrum development screening chart

Definitive Tests for Intellectual & Developmental Assessment

Name of testAge group
Vineland adaptive behavior scale II Birth to 89 years
Bayley scale for Infant development II1 month-3.5 years
Stanford Binet Intelligence scale2 years-85 years
Wechsler Intelligence Scale for Children 6 years-17 years

Intelligence Quotient (IQ)

  • IQ = Mental age/ Chronological age x 100
DegreeIQ Level
Mild ID51 – 70
Moderate ID36 – 50
Severe ID21 – 35
Profound ID0 – 20
Moron50 – 70
Imbecile30 – 50
Idiot< 30
  • The term mental disability is no longer used now. 
  • It has been replaced by the term intellectual disability.

Intellectual Disability

  • Significant impairment in intellectual functioning and social adapting

And that is it! That is everything you need to know about development abnormalities and its types. For more interesting and informative posts like these, keep reading PrepLadder blogs! 


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