Sexual aneuploidy, Lascano and Puno

SEXUAL ANEUPLOIDYLascano, Joshua Ruel A.Puno, Jasmine Nicole S.

Every cell in the human has 23 pairs of chromosomes (for a total of 46). One copy of each pair is inherited from the mother and the other copy is inherited from the father. The first 22 pairs of chromosomes (referred to as autosomes)are numbered from 1 to 22. The 23rd pair of chromosomes are the sex chromosome. Normal females have two X-chromosomes (XX), while normal males have one X-chromosome and one Y-chromosome (XY).

NON-DISJUNCTION OF CHROMOSOME

When Non-disjunction of chromosome happened, the chromosomes did not separate perfectly causing some chromosomes to go to the other pole.

ANEUPLOIDY

Aneuploidy is the term used when there is a change in number of chromosomes. Aneuploidy occurs during cell division when the chromosomes do not separate properly between the two cells. 

SEXUAL ANEUPLOIDY

Sexual Aneuploidy occurs when there is an abnormal change in the number of sex chromosome.

TERMINOLOGY

Monosomy (2n -1) -it refers to lack of one chromosome of the normal

complementDisomy (2n)

-disomy is the presence of having two copies of chromosome. In humans, that have two copies of each chromosome(diploid), it is a normal condition.Trisomy (2n +1)

- it is a condition where there is an extra one chromosome either in the autosomes or sex chromosomesTetrasomy (2n + 2)

-it is a condition where there is two extra chromosomesPentasomy (2n + 3)

-it is a condition where there is three extra chromosomes

5 COMMON ABNORMALITIESSexual Aneuploidy:

KLINEFELTER SYNDROME

It is an abnormal condition that only occurs in males having an extra X-chromosome, having 47 total number of chromosomes (44xxy)

Characteristics:Enlargement of breastUnder developed testes (sterile)Mild-mental Impairment

If for instance they are not sterile, they can produce sperm cells that are:22x (Normal)22y (Normal)22xxy

TURNER SYNDROME

It is an abnormal condition that happens only in females lacking either Y-chromosome or X-chromosome and having only one sex chromosome (X-chromosome), having a total 45 chromosomes (44x)

Characteristics:Webbed-neckedFlat-chestedDoes not exhibit sexual maturation(sterile)

If for instance they are not sterile, they can produce ovum that are:22(no sex chromosome)22x (Normal)

JACOB’S SYNDROME

An abnormal condition that occurs only in males, having an extra Y-chromosome resulting for a total number of 47 chromosomes (44xyy)

Characteristics:Usually violentAntisocial/Uncontrolled temperHigh testosterone level

They are usually fertile, and produces sperm cells that are:22x (Normal)22y (Normal)22yy22xy

METAFEMALE SYNDROME

An abnormal condition that only occurs in females that possesses an X-chromosome, having a total of 47 chromosomes (44xxx)

Characteristics:Generally has a normal appearnace due to Barr Bodies(inactive X-chromosome)Lower female ability (sterile)

If for instance they are not sterile, they can produce ovum that are:22x (Normal)22xx

LETHAL SYNDROME

It is a fatal syndrome that only occurs in male, lacking an X-chromosome(chromosome for life) and only having a Y-chromosome, having a total number of 45 chromosome (44y)

X-chromosome is also called chromosome for life because it carries most of the physiological characteristics.

SAMPLE PROBLEM

IF, FOR EXAMPLE, A PERSON HAS A JACOB’S SYNDROME MARRIES A PERSON THAT HAS A METAFEMALE SYNDROME, ASSUMING SHE IS FERTILE. WHAT IS THE PROBABILITY OF HAVING A NORMAL CHILD AND 3 ABNORMAL CHILDREN?

JACOB’S(44XYY) X METAFEMALE(44XXX)

22X 22X 44XX (NORMAL FEMALE) 44XXY (KLINEFELTER)

22XY 44XY (NORMAL MALE) 44XYY (JACOB’S)22Y

22YY 22XX 44XXX (METAFEMALE) 44XXXY (KLINEFELTER) 44XXY (KLINEFELTER) 44XXYY(JACOB’S)

JACOB’S = 2/8KLINEFELTER = 3/8 ABNORMAL ( 6/8 OR 3/4)METAFEMALE = 1/8MALE= 1/8FEMALE = 1/8 NORMAL ( 2/8 OR ¼)

P = n! RATIO: 3:1 OR (3/4)(1/4) A! (n – A)!WHERE : A - ABNORMAL NORMAL MALE(1/2) n – TOTAL NUMBER OF CHILDREN NORMAL FEMALE (1/2)

P = 4! 4(1) (3) 3

3! (4 – 3)! 4 4 P = 4X3X2X1 = 4(1) (27) 3X2X1 (1)! 4 64 =4 (27) P = 4 = 4(N)(A) 3 256

1 = 108 OR 27 256 64

NOTE:

IN THE EQUATION, THE TOTAL NUMBER USED IS 4 WHERE THE TOTAL NUMBER OF CHILDREN IS 8. WE USED 4 BECAUSE OF THE RATIO INDICATED AND BASE FROM THE PROBLEM WHERE THE ABNORMAL CHILDREN IS 3 AND THE NORMAL CHILD IS 1. ONE THING SHOULD BE REMEMBERED IS THAT THE ANSWER SHOULD ALWAYS BE EXPRESSED IN THE LOWEST TERM.

THE END