Pediatrics at a glance

Dr Salini  G K MD (Hom) Pediatrics

Last moment revisions
Kilonychia is seen in Iron deficiency anaemia
Bitos spot, Keratomalasia are the feature of Vit. A deficiency.
Vit. C deficiency causes scurvy.
Female chromosomal pattern 46 XX.
Uterus and fallopian  is developed from – Mullerian duct.
Streak ovary is associated with Turners syndrome

  • Second Meiotic division occurs after fertilization.
  • Umbilical cord has 1 vein and 2 arteries.
  • Ovum when discharged from the Graffian follicle carries with it a few granulosa cells and is called corona radiata.
  • Prolonged clotting time is a diagnostic feature of Hemophilia.
  • Duodenal atresia – X-ray shows double bubble sign.
  • Pott’s disease – TB spine
  • Child draw circle at 3yrs (36 months)
  • Upper segment lower segment ratio at 3yrs  is 1.4:1
  • Most commonest manifestation of congenital Toxoplasmosis – Chorioretinitis
  • Commonest cause of vomiting in 1 month old infant is Aerophagy
  • In fetus the insulin secretion begins by 12th week.
  • Commonest childhood tumour is ALL
  • Aspergers syndrome is developmental delay.
  • Feco oral root of spread of infection is seen in Hepatitis A and E.
  • By 2yrs all milk teeth are erupted.
  • Water content in an infant – 75-80%
  • Taste perception of baby develops at birth
  • Most common intrauterine infection is CMV
  • Ghon’s focus – Defect most commonly occuring in congenital rubella
  • The hemoglobin appears in fetus is HbF
  • Commonest intra cranial tumour in childhood is Medulloblastoma
  • Celiac disease is due to hyper sensitivity to Wheat.
  • Commonest cause of Neonatal death in INDIA – prematurity
  • The infant with galactosemia should avoid milk. 

Periods  of  growth
A. Prenatal  period

  • Embryo   14  days  to  9  weeks
  • Fetus-       9 weeks  to  birth

B. Perinatal  period

 22 weeks  of gestation  to  7  days  after  birth

C. Postnatal  period

  • Newborn                    first 4 weeks  after birth
  • Infancy                       first  year
  • Toddler                      1 to 3 years
  • Preschool child       3 to 6  years

D. School  age  child

  • 6-10 YRS (GIRLS)
  • 6-12 YRS  (BOYS)

E. Adolescence  : 10-19  yrs.

 The sexual reproduction is divided in to several stages.
 They are:

  1. Gametogenesis
  2. Fertilization
  3. Cleavage
  4. Gastrulation &
  5. Organogenesis.         


  • Process by which the spermatozoa are formed.
  • It takes place in the wall of seminiferus tubule.
  • The total time taken from the begining of the Meiosis to the formation of spermatozoa is about 64 days.
  • 200-300 million sperms are released / ejaculate                                                     


  1. It differs from spermatogenesis.
  2. Oogonia divide to form primary Oocyte in prenatal life.
  3. From prenatal life to puberty the primary Oocyte remain in a suspended prophase it is because of oocyte maturation inhibitor (OMI).
  4. Meiosis I completes at the time of ovulation.
  5. As aging some primary Oocytes complete their meiotic division after 40-years or more. So chance for meitotic error (Nondisjunction).
  • In both Meitotic divisions in Oocyte, there is unequal division of cytoplasm.
  • Primary Oocyte divides to form 1 secondary Oocyte receiving most of the cytoplasm & 1 (first) polar body with hardly any cytoplasm.
  • Both having only haploid chromosome complement.
  • 2nd meiotic division in Oogenesis commences as the female germ cell passes into the uterine tube,but completes only after fertilisation.
  • After fertilization secondary Oocyte completes its second meiotic division & extrudes the second polar body.
  • The ovum  is covered by Oolemma the primary membrane is called the vitelline membrane
  • It is enveloped by secondary membrane called Zona pellucide which is surrounded by radialy arranged cells called corona radiata.
  • These cells are bound together by hyaluronic acid.
  • Tertiary membranes are secreted by the gland cells of oviduct or uterus.

EMBRYOLOGY  is  the study of formation and development of the embryo from the moment of its formation up to the time when it is born as an infant.


  • It occurs mostly in the ampullary part of the uterine tube.
  • It is the process by which haploid male & female gametes come together & fused to form a single diploid cell called zygote.
  • The  Migration  & Union Of Nuclei Of Male and   female gametes is called as amphimixis .
  • The fertilization takes 24 hours to complete. 

About 6 days after fertilization implantation occurs.

(GASTRULATION)  – 3rd week

At very early stage in the development of embryo proper acquire the form of three layers – Embryonic disc.

The three layers are:

  • Endoderm
  • Ectoderm
  • Mesoderm

From these three layers all the tissues of the body are derived.


  • In the 4th week the organogenesis begins.
  • By the end of 8th week, all the major body system have begun to develop, all though their functions are minimal.
  • The cylinder  like embryo consist of the endoderm in the center, ectoderm on the out side & mesoderm in between.
  • The embryonic folding is due to the different rates of growth of the various parts.

FETAL PERIOD (9th week to till birth)

  • During the fetal period tissues & organs that developed during the embryonic period grow & differentiate.
  • Very few new structures appear during the fetal period.
  • The rate of the body growth is remarkable, especially during the 2nd half of IUL.
  • At the beginning of the fetal period, the head is half the length of the body.


  • The fetal circulation differs from adult circulation in some aspect.
  • The blood vessels transverse the umbilical cord & enter the umbilicus of the fetus.
  • Here the umbilical vein carries oxygenated blood from the placenta
  • On approaching the liver  half of the blood passes directly into the ductus venosus and goes to IVC.
  • The other half of the blood in the umbilical vein flows into the sinosiods of liver & enters the IVC through hepatic veins.
  • The IVC enters the Rt atrium of heart.
  • From the Rt atrium the Blood goes to Lt atrium then to Lt ventricle through foramen ovale.
  • Here it mixes with the poorly oxygenated blood returning from lungs through the pulmonary veins.
  • From the Lt atrium blood passes to the Lt ventricle & leaves through the ascending aorta.
  • The branches of the arch of aorta supplies the Head , neck & upper extrimities & venous return to Rt atrium trough superior venacavae.
  •  The small amount of well oxygenated blood from the IVC mixes with poorly oxygenated blood from the SVC in the Rt atrium goes to Rt ventricle. This blood with medium oxygen content leaves through pulmonary trunk.
  • Only a small part of blood passes through the lungs & greater part traversing through the ductus arteriosus which communicates with the aortic arch.


  • Baby is covered with V C.
  • V C is a greasy white substance which is secreted by the fetal sebaceous glands.
  • Color of V C is often a clue to fetal pathology. e.g.
  • Golden yellowish –erythroblastosis fetalis
  • Completely absent – post -maturity

Inspection of umbilical cord should be done carefully, the number of vessels & loosening of ligature to checked.

THE MORO REFLEX:  The first of the primitive reflexes, the Moro emerges around 8-9 weeks in utero and is inhibited at about 16 weeks of neonate life. It is transformed into the adult startle.It should not be present in children beyond one year.

When the baby’s head is turned to one side there will be ipsilateral  extension of arm and leg and felexion of contralateral limb flexion.

Is elicited by placing a finger across the palm or sole. the tightness of grasp is often sufficient to elicit a traction response. It may weak in pre-term or a depressed infant.& also affected side in cases of brachial plexus palsy.

Is tested by touching the cheek of the infant .The normal reaction of an alert term baby is to turn the head towards the stimulus & start sucking.


  • Chin then chest up – 1-2 month
  • Head control – 3 months
  • Roll over (supine to prone) – 4th month
  • Prone to supine – 5th month
  • Sits with support – 6th month
  • Sits without support – 7th month
  • Crawls – 8th month
  • Stands with support – 9th month
  • Walks with support – 11th month
  • Walks without support – 12th month
  • Running – 18th month
  • Walking upstairs –  24th month (2 yrs)


  • Grasps rattle – 3-4 months
  • Reaches objects – 4th month
  • Objects transfer hand to hand – 4-5th month
  • Palmar grasp – 7th mo nth
  • Pincer grasp – 8-9th month
  • Turns pages of book – 12th month
  • Scribbles –  13th month
  • Builds 2 cubes – 15th month
  • Builds 6 cubes – 24th month


  • Turns head to sound – 1month
  • Cooing – 3rd month
  • Monosyllabus  (Ma, Pa) – 6th month
  • Bisyllabus – 9th month
  • 2 words with meaning – 12th month
  • Ten words with meaning – 18th month
  • Simple sentence – 24th month
  • Telling a story  – 36th month


  • Social smile – 2nd month
  • Recognize mother – 3rd month
  • Smiles at mirror image – 6th month
  • Waves bye bye – 9th month
  • Plays small games – 12th month
  • Know genter – 36th month



  • Birth wt                       –  2.5-3Kg
  • Wt at 4-5 months      2 x birth wt
  • Wt  at 1 yr                     3 x birth wt
  • Formula for calculating weight in kg
  • 1-6 yrs             ( age in yrs x 2) + 8
  • 7 -12 yrs           age in yrs x  3

Length / Height

  •  At birth         –         50 cm
  • 1yr                        –           75 cm
  • 4 yrs              –         doubles (100 cm)
  • 12 yrs           –           triples   (150 cm)
  • Formula- 2-12 yrs
  • Age in yrs X 6 + 77 CMS


  • At birth            – 33-35 cm
  • 1yr                   – 45-47 cm
  • 2yr                   – 49cm


  • Measured –level of the nipples, midway between inspiration & expiration , while the child is at the recumbent  position .
  • At birth head circumference is larger than the  chest circumference by  about 3cm
  • 9months-1 year of age –equal
  • HC>CC – at birth
  • HC=CC – at 1 yr
  • HC<CC – after 1yr 


  • Measured – fibre class  or steel tape at the midpoint between  acromion  &  olecranon
  • Between 1 to 5 yrs – >13.5 cm
  • In pre school children , measurement < 12.5 cm means significant  malnutrition


  • Upper/lower segment ratio –
  • At birth -1.7:1
  • The ratio at the age of 3 is 1.3:1
  • After 7 yrs & usually by the age of 10-12 yrs, the ratio becomes approximately 1:1



  • Lower central incisors –  5 & 8 months
  • Upper central incisors –  a month later
  • Lateral incisors          –   next 3  months
  • First molar teeth          –   12- 15 months
  • Canine teeth             – between 18 & 21months
  • Second molar teeth    –    21-24 months
  • By 2 yrs of age  all the milk teeth appears


  • First molar     –  6 years
  • Central  &  lateral  incisors  –  6  to  8  yrs
  • Canines  &  premolars    –  9 to 12  yrs
  • Second  molars                 12 yrs
  • Third   molars               – 18  years or later

COLOSTRUM: It is the milk secreted during the first 3 days after delivery.
It is thick & yellow & contains  more antibodies and white  blood cell

FORE MILK: Is the milk secreted at the start a feed.
It is rich in proteins, sugar, vitamins, minerals & water.

HIND MILK:Comes later towards the end of a feed and is richer in fat content & provides more energy and satiety.
For optimum growth, the body needs the both fore & hind milk.

Erythema infentiosum – 5th disease – Human parvo virus B19
Examthema subitum  ( sudden rash)– Roseola infantum – 6th disease  – sixth rahes seen disease in children – Herps virus 6

Polio virus – smallest virus infects motor neuron cells in the spinal cord (the anterior horn cells) and the medulla oblongata (the cranial nerve nuclei)

Guillain-Barré syndrome  – It is a postinfectious polyneuropathy involving mainly motor, but sometimes also sensory and autonomic recover with in 6 months

Commonest Helminthic infection in children – Enterobiasis

TB in children

  • Primary focus is known as Ghons focus
  • Infraclavicular lesion  of the chronic pulmonary TB is called as Assman’s focus
  • AFB test, Anti tuberculin test
  • Mantoux Test (after  48-72 hours an induration above 10mm suggests tubercular  infection).

Primary Complex
Primary Focus  (Inflamed area at the point of entry Size few mm to 1-2cm.)

  • Draning lymphatics
  • Inflammed lymph nodes

   (It include cervical lymph nodes, hailer lymph nodes, tonsils, mesentric lymph nodes)


  • Learning disability – Commonest cause dyslexia 4 out of 5 children with LD are having dyslexia
  • ADHD – Hyperactivity, impulsiveness and inattention
  • Autism spectrum disorder – Autistic disorder, Asperger’s disorder and Pervasive Developmental Disorder
  • AUTISM – It is a neurodevelopmental disorder with severe language imparement
  • ASPERGER’S DISORDER – They have deficits in nonverbal and pragmatic aspects of communication (facial expressions, gestures).
  • Rett disorder – It is a neurodevelopmental disorder resulting from a genetic mutation. Microcephaly, more seen in girls.
  • VOIDING DISORDERS – Eneuresis, Encopressis


  • Anorexia nervosa (AN)
  • Bulimia nervosa (BN)
  • Binge eating disorder (BED) – no purging 


  • Breath holding spells
  • Kleptomania
  •  Aggression etc


  • Physiologic anemia of infancy – A progressive decline in hemoglobin level begins and persists for 6–8 wk.
  • Erytroblastosis fetalis – Mother Rh –ve father Rh +ve
  • The megaloblastic anemia develops due to Folic acid deficiency, Vitamin B12.
  • Factor VIII or Factor IX Deficiency (Hemophilia A or B)
  • von Willebrand Disease – The most common hereditary bleeding disorder is von Willebrand disease due decreased production of this factor by endothelial cells.

Congestive Splenomegaly (Banti Syndrome)– Splenomegaly may result from obstruction in the hepatic, portal, or splenic veins.

Hypersplenism – Increased splenic function (sequestration or destruction of circulating cells) results in peripheral blood cytopenia, increased bone marrow activity, and splenomegaly.

  • Decreased Surfectant –in preterms
  • Pectus excavatum accounts for >90% of congenital chest wall anomalies –Funnel shaped chest.
  • Pectus carinatum (pigeon breast) is an uncommon sternal deformity accounting for 5–15% of congenital chest wall anomalies
  • Jeune syndrome -Asphyxiating Thoracic Dystrophy (Thoracic-Pelvic-Phalangeal Dystrophy)
  • Kartagener syndrome: – Primary ciliary dyskinesia (PCD) -Situs inversus, chronic sinusitis and otitis, and airway disease leading to bronchiectasis
  • Loeffler syndrome  –  Transient respiratory symptoms like cough and dyspnea, pulmonary infiltrates, and blood eosinophilia due to migrated larvae of ascaris.
  • Larvae may be observed in the sputum.


  • The heart developed from a group of angioblast
  • During gestational week 3 through 8, the major cardiovascular structures develop.
  • Heart begins to beat by the end of 3rd week.
  • The nerves invade the heart at the end of  4th week.
  • The SA node develop by 3rd month of intra uterine life.


  • Ventricular septal defect (Commonest CHD – less clinicaly seen0
  • Atrial septal defect – Common with clinical manifestation
  • Atrioventricular septal defect
  • Patent ductus arteriosus


  • 1) ostium secundum
  • 2)Ostium primum
  • 3)The sinus venosus ASDs

A second opening, ostium secundum, now appears in the central area of the primary septum (allowing continued flow of oxygenated blood from the right to left atria, essential for fetal life).

As the ostium secundum enlarges, the septum secundum makes its appearance adjacent to the septum primum.

This septum secundum proliferates to form a crescent-shaped structure overlapping a space termed the foramen ovale

These lesions result in chronic right-sided pressure and volume overload that eventually causes pulmonary hypertension with reversal of flow and right-to-left shunts with cyanosis (Eisenmenger syndrome).



  • During intrauterine life, the ductus arteriosus permits blood flow from the pulmonary artery to the aorta & bypasses the unoxygenated lungs.
  •  Shortly after birth, the ductus constricts due to increased arterial oxygenation, decreased pulmonary vascular resistance, and declining local levels of prostaglandin E2.
  • Complete obstruction occurs within few months after extra uterine life.


  • Transposition of great arteries
  • Truncus arteriosus
  • Tetralogy of Fallot
  • Total anomalous pulmonary venous connection


It causes for about 5% of all congenital cardiac malformations.
Tetralogy of Fallot is the most common cause of cyanotic congenital heart disease.

 The four features of the tetralogy are

  • (1) VSD
  • (2) Obstruction to the right ventricular outflow tract (sub pulmonary stenosis)
  • (3) An aorta that overrides the VSD
  • (4) Right ventricular hypertrophy

4 types:

  • 1)True Dextrocardia with situs inversus:- There is mirror image transposition of the cardiac chambers.
  • This is usually associated with the mirror image transposition of the abdominal viscera
  • 2) Isolated dextrocardia without situs inversus:- mirror image transposition of the cardiac chambers but no situs inversus .
  • 3) False Dextrocardia or Dextroversion:- There is no mirror image transposition of the cardiac chambers . Heart is merely shifted to the right side of the chest.
  • 4)Secondary Dexocardia:-  In this Heart is shifted to Rt due to various thoracic diseases like fibrosis or collapse of right lung or increased intra plueral pressure in the Lt side.


  • Meningitis
  • Encephalitis
  • Kernicturus ( Hepatoencephalopathy)
  • Tuberculoma

Cysticercosis – Neurocysticercosis

  • Cerebral Palsy – A group of motor syndromes resulting from disorders of early brain development
  • Febrile Seizures – Common till 5yrs of age

Digestive System

  • Hiatal Hernia – Herniation of the stomach through the esophageal
  • Gastroesophageal Reflux Disease (GERD)
  • Esophageal Varices -Portal hypertension is an elevation of portal venous pressure to levels 10–12 mm Hg higher than pressures present in the inferior vena cava, this causes esophageal varices.
  • Inguinal hernias  – One of the most common conditions seen in pediatric age group.
  • Meckel diverticulum – It is a remnant of the embryonic yolk sac, which is also referred to as the omphalomesenteric duct or vitelline duct
  • Duodenal atresia – It  is thought to arise from failure to recanalize the lumen after the solid phase of intestinal development in the 4th and 5th wk of gestation. “double-bubble sign” on plain abdominal radiographs  after 6-12hrs
  • Acute Appendicitis – The peak incidence between the ages of 12 and 18 yr


  • Appears within 24 hours of age
  • Increase of bilirubin > 5 mg / dl / day
  • Serum bilirubin > 15 mg / dl
  • Jaundice persisting after 14 days
  • Stool clay / white colored and urine, staining clothes yellow
  • Direct bilirubin> 2 mg / dl
  • Gilbert’s Syndrome –  fluctuating increases in unconjugated bilirubin caused by decreased ability of the liver to conjugate bilirubin.
  • CRIGLER-NAJJAR SYNDROME – Autosomal recessive defect in hepatocellular excretion of bilirubin glucuronides across the canalicular membrane – unconjugated hyperbilirubinemia
  • Dubin-Johnson and Rotor’s Syndromes – These are characterized by impaired biliary secretion of conjugated bilirubin.
  • Present with a conjugated hyperbilirubinemia that is usually mild


  • Retrograde flow of urine from the bladder to the ureter and renal pelvis is referred to as vesicoureteral reflux.
  • Neuropathic bladder dysfunction in children usually is congenital and may result from neural tube defects or other spinal abnormalities
  • Absent left kidney
  • Renal ectopia – pelvic kidney

Sometimes the kidneys are pushed so close together during their passage through the arterial fork that the lower poles fuse, forming a horseshoe kidney

Exstrophy of the bladder

Diabetes insipidus (DI) – It presents clinically with polyuria and polydipsia and may result from either vasopressin deficiency (central DI) or vasopressin insensitivity at the level of the kidney (nephrogenic DI)

Cretinism – Hypothyroidism in children

Graves disease – Hyperthyroidism – It has a peak incidence in the 11- to 15-yr old

Lymphocytic thyroiditis (hashimoto thyroiditis, autoimmune thyroiditis) – most common cause of thyroid disease in children and adolescents.

Goiter – Enlarged thyroid gland

Hyper parathyroidism – Excessive production of parathyroid hormone (PTH) may result from a primary defect of the parathyroid glands such as an adenoma or hyperplasia (primary hyperparathyroidism).

Cushing Syndrome – It is the result of abnormally high blood levels of cortisol or other glucocorticoids

ADDISON DISEASE – Autoimmune destruction of the glands leads to decreased adrenal hormones.

Type I diabetes – (β-cell destruction, usually leading to absolute insulin deficiency)


  • Clubfoot – Due to compression in uterine  cavity
  • Osteomyelitis – Staphylococcus aureus is the most common infecting organism in all age groups –causes metaphyseal abscess.
  • Legg-Calvé- Perthes Disease – It is a femoral head disorder of unknown etiology.  It involves temporary interruption of the blood supply to the bony nucleus of the proximal femoral epiphysis which  leads to impairment of the epiphyseal growth and femoral head deformity.

Progressive lymphocytic & plsma cell infiltration of salivary &lacrimal glands

  1.  Dry eyes(keratoconjunctivitis sicca)
  2.  Dry mouth(xerostoma)
  3.  With connective disease features

Recurrent oral & genital ulceration with relapsing iritis, uveitis characterised by cutaneous arthritic, neurologic, vascular & G.I.T. Manifesttions.

MUSCULAR DYSTROPHY: – It is a primary myopathy; it has a genetic basis; the course is progressive; degeneration and death of muscle fibers occur at some stage in the disease.

Duchenne muscular dystrophy – It is the most common hereditary neuromuscular disease.

Becker muscular dystrophy – It is the same fundamental disease as Duchenne dystrophy, but clinically it follows a milder and more protracted course.

Scabies – It is caused by burrowing and release of toxic or antigenic substances by the female mite Sarcoptes scabiei var. hominis

PEDICULOSIS CAPITIS  – Head lice (Pediculus humanus capitis)

CHICKENPOX – Varicella-zoster virus (VZV) causes primary, latent.

HERPES ZOSTER – latent infection of sensory ganglion neurons

MOLLUSCUM CONTAGIOSUM – The poxvirus that causes molluscum contagiosum

VIRAL WARTS – Human papillomaviruses (HPVs) cause a spectrum of disease from warts to squamous cell carcinoma of the skin and mucous membranes .

PITYRIASIS ROSEA – This benign, common eruption occurs most frequently in children and young adults.The cause of pityriasis rosea is unknown; a viral agent is suspected and there is debate over the role of human herpesvirus 7.

ORAL CANDIDIASIS – Candidiasis is the most common fungal infection in the world. They are of 3 types:

  • 1) Yeast cells
  • 2) Chlamydospores
  • 3) Pseudomycelium

TINEA VERSICOLOR – Chronic fungal infection of the stratum corneum is caused by the dimorphic yeast Malassezia furfur. The synonyms Pityrosporum ovale and P. orbiculare were used previously to identify the causal organism.

VITILIGO – It has been suggested that melanocytes are destroyed because of the accumulation of a toxic melanin synthesis intermediate

ALBINISM – In this there is  partial or complete failure of melanin production in the skin, hair, and eyes despite the presence of normal number, structure, and distribution of melanocytes


  • Malignant tumor arising from embryonal cells
  • Nephroblastoma
  • Retinoblasoma
  • Neuroblastoma
  • Medulloblastoma


  • Primary central nervous system (CNS) tumors are the second most frequent malignancy in childhood and adolescence.
  • Medulloblastoma, accounting for 90% of embryonal tumors.
  • Neuroblastoma
  • NB is the most frequently diagnosed neoplasm in infants.
  • The median age at diagnosis is 2 yr; 90% of cases are diagnosed before 5 yr of age.
  •  The incidence is slightly higher in males and in whites.


  • Other wise known as nephroblastoma.
  • Wilms’ tumor/ cancer of the kidneys that usually affects children by 5 years of age
  • It may also occur in the fetus.
  • It is the most common malignant tumor of the kidney.
  • In the childrens there will be deletion in the region of  11th chromosome in p13 position


  • Retinoblastoma is a rare malignant tumor arising in one or both eyes of children
  • The locus of the retinoblastoma gene is on the long arm of chromosome 13
  • The loss of gene during mitotic chromosomal process may cause the tumor. 


  • Most osteosarcomas occur during adolescence.
  • About half of them arise in the metaphysis around the knee, either in the distal femur or proximal tibia.
  • X- ray – Sun ray spicules
  • Osteosarcoma of the upper end of the tibia.


  • It is a primary bone tumour.
  • Ewing sarcoma is a primitive neuroectodermal tumor
  • It is seen mostly in 1st decade (1-10 Years)
  • Most common site is Diaphysis of bone
  • Hard swelling in the  middle of long bone.
  • It is fusiform shaped & on X-ray examination it looks like onion peal.
  • Conformation of diagnosis by tissue biopsy & FNAC
  • Treatment:- Radio-therapy.

Osteosarcoma is the most common primary malignant bone tumor in children and adolescents
Next common is Ewing sarcoma


  • Hodgkin disease accounts for about 5% of cancers in persons younger than 15 yr of age and for about 15% in persons 15–19 yr of age.
  • 3 forms
  •  A childhood form (≤ 14 yr of age)
  • A young adult form (15–34 yr of age) &
  • An older adult form (55–74 yr of age).
  • The Reed-Sternberg cell, a large cell with multiple or multilobulated nuclei, is considered the hallmark of Hodgkin disease.
  • Reed-Sternberg cell arises from germinal center B-cells in most cases


  • Down’s syndrome involves trisomy of chromosome 21.
  • Main cause is increased maternal age. 


  • Turner’s syndrome having 45 X Genotype.
  • In this there is a considerable degree of chromosomal mosaicism eg. 45 X 46 XX.

Autosomal Dominant: Vertical transmission from parent to child
AD disorder have a fault in one or other copy of the two genes    Eg: Marfan Syndrome             


  • Caused by a mutation in the gene encoding fibrillin, which is required for structural integrity of connective tissues.
  • The major tissues affected are the skeleton, eyes and cardiovascular system.


  • Tall stracture
  • Long fingers
  • Bilateral subluxation of lens
  • Floppy mitral valve
  • Aortic aneurysm
  • Aortic dissection

Autosomal recessive  inheritance:
Recessive traits & disorders are only manifest when the mutant allele is present in a double dose ie, homozygosity

  • Beta-Thalasemia
  • Haematological-Sickle cell Anaemia
  • Endocrine-Congenital adrenal hyperplasia
  • Galatosemia
  • Metabolic-Cystic fibrosis

Sex linked inheritance:
Pattern of inheritance shown by the genes which are located on either of the sex chromosomes
Eg : – for X-linked;

  • Haemophilia
  • Partial colour blindness
  • Vit-D resistant rickets

Eg: – Y-linked-Hairy pinna



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