Showing posts with label Genetics. Show all posts
Showing posts with label Genetics. Show all posts

Thursday, November 4, 2010

-Duhin-Johnson syndrome.

Duhin-Johnson syndrome.
It is Autosomal recessive disease characterized by Partial defect in excretion of conjugated bilirubin into the bile.

*Clinical picture:-It is usually asymptomatic.
  1. Jaundice.
  2. Good general condition.
*Investigations:-
  1. Bilirubin: mild elevation of direct bilirubin
  2. Biopsy (dark pigment inside hepatocytes i.e the liver is black in colour), it had been proved to be a metabolite of catecholamines.
  3. +ve Bromosulphthalein (BSP) Test: Normally 90% of this dye is removed from blood within 45 minutes after I.V injection in normal liver.
  4. In Dubin-Johnson syndrome there is a late rise in plasma SSP after an initial fall due to reflux of the dye from the liver reflecting hepatic excretion defect.
  5. No evidence of obstruction.
  6. No evidence of LCF.
*Treatment:-
No treatment (almost normal life span).

Dr Ibrahim
Return to list of medical syndromes here

Thursday, January 28, 2010

- Kallmann syndrome.

 Kallmann syndrome


- Def :- It is a rare X-linked recessive genetic disease which characterized by delayed or absent puberty and an impaired sense of smell, also referred as olfactogenital dysplasia.

- Kallmann syndrome is a form of secondary hypogonadism, reflecting that the primary cause of the defect in sex-hormone production lies within the pituitary and hypothalamus rather than a physical defect of the testes or ovaries.

- Kallmann syndrome was described in 1944 by Franz Josef Kallmann, a German-American geneticist.(1)(2)

- Incidence:-
It affects primarily males at an incidence of 1 out of 10,000 in a study of French conscripts.(3)
The male-to-female ratio ranges from 4:1 to 5:1.

- Cause:-
Mutations in the KAL1, FGFR1, PROKR2, and PROK2 genes cause Kallmann syndrome.
These genes play a role in the development of certain areas of the brain before birth. Although some of their specific functions are unclear, these genes appear to be involved in the formation and movement (migration) of a group of nerve cells that are specialized to process smells (olfactory neurons).(4)

- Synonyms:-
  • de Morsier’s syndrome II.
  • Morsier-Gauthier syndrome.
  • Kallmann-de Morsier syndrome.
  • Maestre-Kallmann-de Morsier syndrome.
  • Maestre de San Juan-Kallmann syndrome.
  • Maestre de San Juan-Kallmann-de Morsier syndrome.
  • anosmic hypogonadism.
  • anosmic idiopathic hypogonadotropic hypogonadism.
  • hypogonadotropic hypogonadism and anosmia.
  • hypogonadotropic hypogonadism-anosmia syndrome.

Wednesday, January 27, 2010

- Sertoli-cell-only syndrome (germinal cell aplasia).

Sertoli-cell-only syndrome (SCO)
-Def:- It is a condition in which only Sertoli cells line the seminiferous tubules of the testes and characterized by male sterility (due to azoospermia) without sexual abnormality.
- Synonyms:-
  • Del Castillo syndrome.
  • Germ cell aplasia.
-The etiology (1):-
  • Most causes of SCO syndrome are idiopathic. A congenital absence of germ cells due to failure of migration of gonocytes is theoretically possible.
  • Massive deletions in the azoospermia factor (AZF) region of the Y chromosome. found.
  • Exposure to chemicals and toxins may cause SCO; however, direct cause-and-effect relationships in humans have been difficult to document.
  • Klinefelter syndrome, 47 XXY, results in a characteristic biopsy appearance of SCO and Leydig cell hyperplasia.

Wednesday, January 13, 2010

- Metabolic syndrome (Syndrome X).

 Metabolic syndrome
-Def :- It is a combination of medical disorders that increase the risk of developing cardiovascular disease and diabetes (1).

-Synonyms :-syndrome X, insulin resistance syndrome, Reaven's syndrome or dysmetabolic syndrome.

 

Wednesday, December 16, 2009

- Oculo-cerebro-renal Syndrome.

Oculo-cerebro-renal Syndrome


-Def:- It is a X-linked recessive disorder of eye,cerebral cortex and renal tubules .

-Synonyms (1):-
  • Lowe's oculocerebrorenal disease/syndrome.
  • Lowe's disease/syndrome.
  • Oculocerebrorenal dystrophy.
- The condition became known as "Lowe syndrome" named after Dr. Charles Lowe, the senior member of the group that described it.

-Clinical picture:-

Friday, December 4, 2009

- Fanconi's syndrome.


"Fanconi's syndromes"

* There are many types of Fanconi's syndrome according to
etiology
:-


-Primary type
-Hereditary:-
  • Abderhalden-Kaufmann-Lignac syndrome "cystinosis" (click here).
  • Oculo-cerebro-renal Syndrome (Lowe's Syndrome) (click here).
  • Galactosemia.
  • Wilson disease.
-Drug induced:-
  • Out dated tetracycline.
  • Cyclosporin.
  • Heavy metals (e.g lead poisoning).

*Fanconi's syndrome ( primary type)*

-Def:- it is an autosomal recessive disorder due to multiple defects in proximal renal tubules which decrease the urinary re-absorption of phosphate,bicarbonate,glucose, amino acids and may be Potassium ( they all are lost in urine).

-It is named after Guido Fanconi, a Swiss pediatrician.

-Clinical picture:-

Tuesday, November 10, 2009

- Pedigree.

-A pedigree:- is a diagram of a family history and illustrates relationships among family members; it shows which family members are affected with specific medical conditions.

-Information for a three-generation pedigree should be obtained from a family being evaluated for a genetic disorder.

- The patient through whom the family is ascertained is called the proband.


(Symbols commonly used in pedigree chart)


-Consanguinty:-

There are Five degrees of Consanguinty:-

*first-degree:-
-First-degree relatives share half of their genetic material with the proband (brothers, sisters, children,parents).

*second degree:-
-Second degre relatives share one fourth of their genetic material (grandparents,aunts,uncles).

*Third degree:-
-Third degree relatives share one eighth of their genetic material with the proband(1st cousin).

*Fourth degree:-
-Fourth degree relatives share one sixteenth of their genetic material with the proband(2nd cousin).

*Fifth degree:-
-Fifth degree relatives are once remote form the proband.


References:-
(1)Richard E Behrman,Nelson Textbook of Pediatrics,17th ed,ch69,(http://www.elsevier.com).
(2)Bennett RL, Steinhaus KA, Uhrich SB, et al: Recommendations for standardized pedigree nomenclature. J Genet Counsel 1995;4:267–79.)

Monday, November 9, 2009

- All you need about "Down´s syndrome".

-History:-

English physician John Down first characterized Down
syndrome as a distinct form of mental disability in 1862 due to
his perception that children with Down syndrome shared physical
facial similarities (epicanthal folds) with those of Mongolian race.

-Incidence:-
  • In general population 1:660.
  • It is the most common Autosomal abnormalities.
  • It has equal sex distribution.
-Causes (cytogenic types):-

1-Complete Trisomy 21 (non disjunction):-

-Incidence:- 95%.

-Due to non-disjunction of chromosome 21 during meiotic division (

(i.e failure of a chromosome 21 pair to separate) so an ovum with

24 chromosomes when fertilized by a sperm carrying 23

chromosomes
lead to formation of a fertilized ovum with

47 chromosome.


-It occur during oogenesis more than spermatgenesis.

-The risk increases with age of the pregnant mother especially

over 40years as the primary oocytes of the mother have satyed in

the prophase for a long time ( 40 years or more).

-Karyotyping:-

47,xx+21(female down).

47,xy+21(male down).

(+ means that an extra chromosome is present).

(Non disjunction in mother)

2-Mosaic Down´s syndrome:-

-Incidence:- 1%.
-It is the best type.
-Due to non-disjunction of chromosome 21 occurig early in the
division of zygote (i.e after zygote formation) which results in
formation of two cell lines (normal & trisomic).

-Karyotyping:-
some cells as non-disjunction type & the other are normal.

-Clinical manifestaions are less than complete triosomy.


3-Translocation Down Syndrome:-

-Incidence:- 4%.
-Due to unbalanced translocation of chromosome 21 to another
chromosome in group D (usually chromosome 21) or to another
chromosome in group g resulting in phenotype same as trisomy 21
Down syndrome but genotype is 46 chromosome.

-It is the most serious type.

-Robertsonian translocations is the most common type.


-Clinical manifestaions:-

1-conatant features:-
  • Physical growth retardation.
  • Mild to moderate degrees of mental retardation.
  • Hypotonia.
2-Head:-
  • Brachycephaly(flat occipit).
  • silky hair.
  • Microcephaly.
  • Wide anterior fontanel.
  • Delayed closure of posterior fontanel.
3-Eye:-
  • upward slanting eyes.
  • Medial epicanthal folds(extra skin folds at the medial
  • corners of the eyes).
  • narrow palpebral fissures.
  • Brushfield spots iris(speckled irises).
  • hypertelorism.
  • cataract.
4-Ears:-
  • small.
  • low set.
  • Backward displacment.
5-Neck:-
  • Short.
  • webbed.
6-Nose:-
  • small.
  • depressed nasal bridge.
7-Heart:-
  • Congenital HD(50%)
  • Most common(Av canal,VSD).
8-Tongue:-
  • Protruded (small oral cavity).
  • fissured.
9-Ribs:-
unilateral or bilateral absence of one rib.

10-Abdomen:-
  • Duodenal atresia.
  • Imperforate anus.
  • Umbilical hernia.
  • Congenital mega colon.
  • Distended abdomen(Due to hypotonia).
  • Diastasis recti.
11-Hands:-
  • Brachydactyle(short & stocky).
  • Clinodactyly i.e incurved little fingers(due to rudimentary or absent middle phalanx of little finger as it the last phalanx to develop).
  • Simian creases:- may be partial or complete.
  • Ridges hypoplasia.
12-Foot:-
  • Syndal gap (i.e wide space between the big toe & second toe).
  • syndal line(i.e deep planter crease).
13-Others:-
  • Hypothyrodism(15%).
  • cryptorchidism.

- Complications:-
  • Accidents due to mental retardation.
  • Heart failure due to Congenital HD.
  • Recurrent Infections (chest,Otitis media,sinusitis) due to decrease immunity,hypotonia,aspiration.
  • They are liable to leukemia "20 times more than general population.
  • GIT complications.
  • Arrythmia which is the cause of sudden death.

-Investigations:-

(A)Prenatal diagnosis:-
  • Amniocentesis
  • chrionic villous sampling
  • Karyotyping
  • Triple test
(b)After birth:-
  • Karyotyping:- is dianostic.
  • For Cvs:-Echo,ECG.
  • For blood:CBC to exclude leukemia.
  • Baruim for GIT anomalies.
  • Radiology for U.T anomalies.
  • Thyroid function tests (T3,T4,TSH).

-Treatment:-

- Treatment of congenital anomalies & associated disorders.
- Social,educational& behavioral therapy in special institutes.


*References:-

(1)Langman’s Medical Embryology 9th ed,ch1,p.g11.
(2)Priciples of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g72,73.
(3)Richard E Behrman,Nelson Textbook of Pediatrics,17th ed,Ch70,
(http://www.elsevier.com).
(4)Down syndrome from Wikipedia,here


Return to list of medical syndromes here

Friday, October 23, 2009

- Medical syndromes.

Medical syndrome is defined as :-
A group of symptoms and signs that collectively indicate or characterize a disease, psychological disorder, or other abnormal condition.
There are a lot of medical syndromes and we try to list some of them:-
1-Down syndrome (click here).
2-Plummer-Vinson syndrome (click here).
3-Ramsay Hunt syndrome (click here).
4-Wolf-Hirschhorn Syndrome (click here).
5-Cri-du-chat syndrome (click here).
6-YY syndrome (click here).
7-Klinefelter's syndrome (click here).
8-Turner's syndrome (click here).
9- Fanconi syndrome (click here).
10-Abderhalden-Kaufmann-Lignac syndrome (click here) .
11-Light Wood-Albright syndrome(Lightwood syndrome)(click here).
12-Oculo-cerebro-renal Syndrome (click here).
13-Metabolic syndrome (click here).
14-Pickwickian syndrome (click here).
15- Kallmann syndrome (click here).
16-Sertoli-cell-only syndrome (click here).
17-Lambert-Eaton syndrome (click here).
18-Guillain Barré syndrome (click here).
19-Horner's syndrome (click here).
20-Brown-Séquard syndrome. (click here).
21-Carpal tunnel syndrome. (click here).
22-Sjögren's syndrome (click here).
23-Felty's syndrome (click here).
24-Caplan's syndrome (click here).
25-Congenital Rubella Syndrome  (click here).
26-Caroli's syndrome.  (click here).
27-Malabsorption syndrome.  (click here).
28-Duhin-Johnson syndrome.  (click here).
29-Exploding head syndrome. (click here). 
If you have other syndromes plz tell us...
Dr Ibrahim,,

Tuesday, October 13, 2009

-Genetics in Pediatrics.

We study genetics in Pediatrics mainly for the follwoing reasons:-
  • Major component and/or reason for pediatric admissions.
  • The main cause of death in first year of life.
  • Nearly 71% of children in hospital have a genetic disease or susceptibility.
  • Nearly 3% of newborns with significant birth defect.
  • Families have concerns about recurrence, cause and available therapie.

Wednesday, July 2, 2008

-Turner Syndrome.

Turner Syndrome

*Def :- It is a condition in which a female has only one X sex chromosome instead of XX in her cells (i.e XO or monosomy ) (1).

*Synonyms:-
  • Ullrich-Turner syndrome.
  • Gonadal dysgenesis (2).
*Pathophysiology:-
- Most commonly due to non-disjunction of chromosome X during formation of ova so ovum with one X
chromosome when fertilized an by sperm carrying X chromosome give baby with XO.
- It occurs also in normal ovum when fertilized with sperm neither X nor Y .

* Although in females,only one X chromosome is active , the presence of two X chromosomes is essential for development of the ovaries (1).

*Karyotype (1) :- 45,XO

*Buccal smear:- -ve Barr's body.

*Hormonal assay:- decrease sex hormones.

* Clinical picture (1):-
  • Short stature ( most common presentation).
  • Lymphedema (swelling) of the hands and feet
  • Broad chest (shield chest) and widely-spaced nipples
  • Low hairline
  • Low-set ears
  • infertility ( due to ovarian dysgenesis)
  • Amenorrhea, or the absence of a menstrual period
  • Increased weight, obesity
  • Shield shaped thorax of heart
  • Shortened metacarpal IV (of hand)
  • Small fingernails
  • Characteristic facial features (e.g hypertelorism,epicanthic fold,narrow maxilla)
  • Webbed neck from cystic hygroma in infancy.
  • Congenital heart diseases in 35% of cases mainly Coarctation of the aorta.
  • Poor breast development.
  • Congenital renal diseases (e.g Horseshoe kidney).
  • Cubitus valgus ( wide carrying angle).
  • Mental development is subnormal "but intelligence is normal".
*Prognosis:-
While most of the physical findings in Turner syndrome are harmless, there can be significant medical problems associated with the syndrome.

*Treatment:-
As a chromosomal condition, there is no cure for Turner syndrome. However, much can be done to minimize the symptoms. For example:-(3)
  • Growth hormone, either alone or with a low dose of androgen, will increase growth and probably final adult height. Growth hormone is approved by the U.S. Food and Drug Administration for treatment of Turner syndrome .(3)
  • Estrogen replacement therapy at 14-15 years has been used since the condition was described in 1938 to promote development of secondary sexual characteristics.Estrogens are crucial for maintaining good bone integrity and tissue health (3).
Return to list of medical syndromes here

*References:-
(1) Principles of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g76.
(2)James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0721629210.
(3)Turner Syndrome Society of the United States. "FAQ 6. What can be done? Retrieved 2007-05-11.

Wednesday, June 25, 2008

- Klinefelter's syndrome.

Klinefelter's syndrome

*Def:- It is a condition in which males have an extra X sex chromosome (i.e XXY) in his cells(1).

*Incidence:-
  • The most common sex chromosome disorder (2).
  • The second most common condition caused by the presence of extra chromosomes.
  • Roughly it occur by 0.1% in males.
* Klinefelter syndrome is named after Dr. Henry Klinefelter, an endocrinologist at Massachusetts General Hospital in Boston, Massachusetts, who first described it in 1942 (3).

*Pathophysiology
(1):-
  • Most commonly Due to non-disjunction of chromosome X at one of the meiotic divisions so an ovum with XX chromosome when fertilized by a sperm carrying Y chromosome lead to formation of baby with XXY .
  • less commonly,the condition arise when a normal ovum is fertilized by XY sperm .
  • The condition may appear with XXXY or XXXXY due to non-disjunction at both meiotic divisions this will lead to more mental retardation.
*Karyotype (1) :-
  • 47,XXY
  • 48,XXXY
  • 49,XXXXY
*Buccal smear:- +ve Barr's body.

*Hormonal assay:- decrease androgens.

*Clinical picture:-

  • Infertility.
  • Gynecomastia.
  • Subnormal intelligence or Mental retardation.
  • microorchidism (i.e. small testicles)(4).
  • Absence of body hair.
  • Long stature (due to absence of androgens which help closure of epiphysis).

Return to list of medical syndromes here

*References:-
(1) Principles of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g75.
(2)James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. p 549. ISBN 0721629210.
(3)Klinefelter, HF Jr; Reifenstein, EC Jr & Albright (1942), "Syndrome characterized by gynecomastia, aspermatogenesis without a-Leydigism and increased excretion of follicle-stimulating hormone", J Clin Endocrinol Metab 2: 615–624. Klinefelter, HF (1986), "Klinefelter's syndrome: historical background and development", South Med J 79(45): 1089–1093 talks about the history of the development of the literature.
(4)Leask, Kathryn (October 2005). "Klinefelter syndrome" (HTML). National Library for Health, Specialist Libraries, Clinical Genetics. NationalLibrary for Health. . Retrieved 2007-04-07.

Monday, June 16, 2008

- YY syndrome.

YY syndrome

*Def :- A genetic condition where males have an extra Y chromosome (i.e XYY) in each of their cells .

* This is not usually an inherited condition but a defect that occurs during cell division.

* Often the condition is asymptomatic.

* Incidence :- rare disease.

*Synonyms:-
  • Diplo-Y Syndrome.
  • Polysomy Y.
  • XYY Chromosome Pattern.
*Pathophysiology:-
Due to non-disjunction of chromosome Y during 2nd meiotic division so
YY sperm when fertilizes an ovum carrying X chromosome give baby with XYY.

*Karyotype :-
47,XYY

* Clinical picture:-
  • Tall stature
  • Subnormal intelligence.
  • Developmental delays.
  • May show aggressive tendency or antisocial behavior.

Return to list of medical syndromes here

*References:-
- Principles of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g75,76.

Tuesday, June 10, 2008

- Cri Du chat syndrome.

Cri Du chat syndrome

*Synonyms:-
  • chromosome 5p deletion syndrome.
  • 5p minus syndrome.
  • Lejeune’s syndrome.
*Incidence:- rare.

*Pathophysiology:-
results from deletion of the distal short arm of chromosome no 5 (1).

*Karyotype :-
46,xx,5p-(female).
46,xy,5p-(male).
(5p- means that the short arm of chromosome 5 is shorter than normal).

*Clinical picture:-
  • characteristic cry of affected infants, which is similar to that of cat ( i.e a high-pitched cry ) due to problems with the larynx and nervous system,about 1/3 of children lose the cry by age 2.
  • feeding problems because of difficulty swallowing and sucking.
  • low birth weight
  • growth retardation.
  • Mental retardation.
  • hypotonia.
  • microcephaly.
  • cardiac defects (eg, ventricular septal defect [VSD],atrial septal defect [ASD], patent ductus arteriosus [PDA], tetralogy of Fallot).

*Treatment:-
  • No specific treatment is available for this syndrome.
  • The mental retardation must be addressed.

Return to list of medical syndromes here

*References:-
Principles of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g74.

Friday, June 6, 2008

- Wolf-Hirschhorn Syndrome.

Wolf-Hirschhorn Syndrome

*Pathophysiology:-
results from deletion of the distal short arm of chromosome no 4 (1).

* Clinically, the minimal diagnostic criteria for Wolf-Hirschhorn syndrome (ie, ‘‘core’’ phenotype) consists of typical facial appearance , mental retardation, growth delay, hypotonia and seizures (or EEG anomalies)(2).

* Different categories of the Wolf-Hirschhorn syndrome phenotype are defined according to the extent of the chromosome.4 deletion(2):-
  • 1st category :- caused by small deletion that is usually associated with a mild phenotype, lacking major malformations. This category is likely under-diagnosed.
  • 2nd category :- caused by large deletions that cause the widely recognizable Wolf-Hirschhorn syndrome phenotype.
  • 3rd category :- caused by very large deletions that cause a severe phenotype that can hardly be defined as typical Wolf-Hirschhorn syndrome.

* Factors affecting prognosis include (2):-
  • extent of the deletion.
  • occurrence of complex chromosome anomalies.
  • severity of seizures.
*Karyotype (1):-
46,xx,4p-(female).
46,xy,4p-(male).
(4p- means that the short arm of chromosome 4 is shorter than normal).

* Clinical picture(3),(4):-
  • Growth retardation.
  • CNS:- Developmental delay and mental retardation of varying degree,microcephaly, seizures, congenital hypotonia with muscle hypotrophy particularly of the lower limbs.
  • Skull:- Frontal bossing, high frontal hairline, hemangioma over forehead or glabella, scalp defect with or without underlying bony defect.
  • Face:- Characteristic features including prominent glabella, hypertelorism, broad beaked nose, and frontal bossing, collectively described as "Greek warrior helmet" facies.
  • Eyes:- Hypertelorism, down-slanting palpebral fissures, epicanthal folds, strabismus, coloboma, proptosis.
  • Nose :- Broad or beaked nose, nasolacrimal duct stenosis or atresia
  • Mouth:- Short upper lip, short philtrum, cleft lip or palate, bifid uvula, carplike mouth, micrognathia, retrognathia
  • Teeth:- Hypodontia
  • Ears:- Low-set ears; large, floppy, or misshapen ears; microtia; preauricular dimples; chronic otitis media with effusion; sensorineural hearing loss.
  • Cardiovascular:- Atrial septal defect, ventricular septal defect.
  • Pulmonary:- lung hypoplasia secondary to diaphragmatic hernia.
  • GIT:- Diastasis recti, umbilical or inguinal hernias, accessory spleens, absent gallbladder, diaphragmatic hernia, intestinal malrotation.
  • Genitourinary:- Hypoplastic kidneys, cystic dysplastic kidneys, unilateral renal agenesis, hydronephrosis, exstrophy of bladder, hypoplastic external genitalia.
  • Skeletal:- Long slender fingers with additional flexion creases, long narrow chest, hypoplastic widely spaced nipples, hypoplasia or duplication of thumbs and great toes, hypoplasia of pubic bones.

Return to list of medical syndromes here


*References:-
(1) Principles of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g74.
(2) Zollino M, Murdolo M, Marangi G, et al. On the nosology and pathogenesis of
Wolf-Hirschhorn syndrome: genotype-phenotype correlation analysis of 80 patients
and literature review. Am J Med Genet C Semin Med Genet. Nov 15 2008;148C(4):257-69. [Medline].

(3)Battaglia A, Carey JC, Wright TJ. Wolf-Hirschhorn (4p-) syndrome. Adv Pediatr. 2001;48:75-113. [Medline].
(4)South ST, Whitby H, Battaglia A, Carey JC, Brothman AR. Comprehensive analysis of Wolf-Hirschhorn syndrome using array CGH indicates a high prevalence of translocations. Eur J Hum Genet. Jan 2008;16(1):45-52. [Medline]. [Full Text].

Thursday, June 5, 2008

- Chromosomal anomalies (aberrations).

- Defenition:-

is a deviation from the normal number (numerical aberrations)or the normal shape(morphology) of chromosomes(structural aberrations).

- Origin:-
(1)Chromosomal anomalies at germ cell level.


-It originates during the formation of germ cells.
-It present in all body cells.
-It appear in karyotyping.
-It may involve Autosomes or sex chromosomes.

*Anomalies involving Autosomes may be:-:-
*Anomalies involving sex chromosomes may be:-
(2)Chromosomal anomalies at somatic cell level.

-It originates during the formation of somatic cells.
-It present in certain cell population.
-It doesnot appear in karyotyping(i.e normal karyotype),but appear in karyotyping of the affected cells.
-It may involve Autosomes & may be:-
  • Numerical e.g polyploidy,aneuploidy.
  • Structural e.g philadelphia chromosome.

-Causes:-
  • Teratogens.
  • Pregnancy in old age.
  • Family history of Chromosomal anomalies.

*References:-
-Priciples of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g70,71,72,78.