1 Principles of Diagnosis of Genetic Diseases using Molecular and Cytogenetic Dr Pupak Derakhshandeh, PhD Ass Prof Medical Science of Tehran University English Website: Persian Website:

2 Cytogenetics

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5 Karyotype 46 ), Xy)

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7 How Chromosome Abnormalities Happen? MeiosisMitosis Maternal Age Environment

8Meiosis

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10 Chromosome abnormalities Abnormality of chromosome number or structure: Abnormality of chromosome number or structure: Numerical Abnormalities Numerical Abnormalities Structural Abnormalities Structural Abnormalities

Down Syndrome Trisomy 21

12 Down Syndrome (Trisomy 21( Trisomy 2(

13 Down Syndrome

14 Frequency of Dysmorphic Signs in Neonates with Trisomy 21 Dysmorphic sign Frequency (%) Flat facial profile 90 Poor Moro reflex* 85 Hypotonia 80 Hyperflexibility of large joints 80 Loose skin on back of neck 80 Slanted palpebral fissures** 80

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16 Frequency of Dysmorphic Signs in Neonates with Trisomy 21 Dysmorphic sign Frequency (%) Dysmorphic pelvis on radiograph 70 Small round ears 60 Hypoplasia of small finger 60

17. Maternal Serum Screening FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.. FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.. FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8.FIGURE 1. Estimated risk of Down syndrome according to maternal age. Data from reference 8. Estimated risk of Down syndrome according to maternal age

18 The risk of having a child with Down syndrome 1/1,300 for a 25-year-old woman; 1/1,300 for a 25-year-old woman; at age 35, the risk increases to 1/365 at age 35, the risk increases to 1/365 At age 45, the risk of a having a child with Down syndrome increases to 1/30 At age 45, the risk of a having a child with Down syndrome increases to 1/30

19 Ultrasound During the first trimester of the majority of pregnancies During the first trimester of the majority of pregnancies measure the size of the fluid area at the back of the fetus’s neck measure the size of the fluid area at the back of the fetus’s neck nuchal translucency or NT nuchal translucency or NT increasing size of the NT: increasing size of the NT: a greater risk of the fetus having Down’s syndrome a greater risk of the fetus having Down’s syndrome

20Ultrasound

21 Trisomy 18, 47 Ch.

22 Trisomy 18, 47 Ch.

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24 Trisomy 18, 47 Ch. incidence of about 1 in 3,000 incidence of about 1 in 3, percent of affected newborns die within the first month 30 percent of affected newborns die within the first month 50% by two months 50% by two months and 90% by one year. and 90% by one year. severe mental retardation severe mental retardation microcephaly microcephaly overlapping fingers, and rocker bottom feet overlapping fingers, and rocker bottom feet Neurologically they are hypertonic Neurologically they are hypertonic Other common malformations include congenital heart, kidney,.... abnormalities. Other common malformations include congenital heart, kidney,.... abnormalities.

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26 Trisomy 13 (XX/XY, 47 Ch) has an incidence of 1 in 5,000 has an incidence of 1 in 5, percent of affected newborns succumb in the first month of life 44 percent of affected newborns succumb in the first month of life and 69% by six months and 69% by six months Only 18% of the babies born with trisomy 13 survive the first year Only 18% of the babies born with trisomy 13 survive the first year microcephaly microcephaly microophthalmia (small eyes) microophthalmia (small eyes) cleft lip or cleft palate cleft lip or cleft palate polydactyly (extra fingers) polydactyly (extra fingers) congenital heart defects congenital heart defects urogenital defects urogenital defects brain malformations brain malformations severe mental retardation. severe mental retardation.

27 Turner Syndrome ( 45, X) 45, X

28 Turner Syndrome (45, X)

29 Turner syndrome Only females Only females One X chromosome One X chromosome Or has two X chromosomes but one is damaged Or has two X chromosomes but one is damaged Short stature Short stature Delayed growth of the skeleton Delayed growth of the skeleton Sometimes heart abnormalities Sometimes heart abnormalities Usually infertile due to ovarian failure Usually infertile due to ovarian failure Short neck with a webbed appearance Short neck with a webbed appearance

30 Kleinefelter/47XXY

31 KleinefelterXXY

32 Klinefelter syndrome (47, XXY) In boys and men In boys and men 47 chromosomes with XXY sex chromosomes 47 chromosomes with XXY sex chromosomes XXY is one of the most common chromosomal abnormalities XXY is one of the most common chromosomal abnormalities 1 in 500 male births 1 in 500 male births the most common genetic cause of male infertility the most common genetic cause of male infertility Often : undiagnosed : variation in clinical presentation Often : undiagnosed : variation in clinical presentation Small testes, insufficient production of testosterone, and infertility Small testes, insufficient production of testosterone, and infertility

33 Fragile X Syndrome

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35 Fragile X Syndrome 1 in 3,600 males 1 in 3,600 males It is second only to Down Syndrome as a cause of mental retardation It is second only to Down Syndrome as a cause of mental retardation

36 Fragile X Syndrome (CGG)n trinucleotide expansion in the FMR1 gene leading to the typical Martin-Bell phenotype (CGG)n trinucleotide expansion in the FMR1 gene leading to the typical Martin-Bell phenotype Expansion of a (CCG)n repeat in the FMR2 gene corresponds to the FRAXE fragile site Expansion of a (CCG)n repeat in the FMR2 gene corresponds to the FRAXE fragile site but it is less frequent and lacks a consistent phenotype but it is less frequent and lacks a consistent phenotype

37 a woman having amniocentesis

38 AF ( weeks)

39 CVS ( weeks)

40 Ultrasonographic Findings Associated with Fetal Down Syndrome Chorionic villus sampling 10 to 12 weeks 0.5 to 1.5 % Early amniocentesis 12 to 15 weeks 1.0 to 2.0 % Second-trimester amniocentesis 15 to 20 weeks 0.5 to 1.0 %

41 Chromosome abnormalities Abnormality of chromosome number or structure: Abnormality of chromosome number or structure: Numerical Abnormalities Numerical Abnormalities Structural Abnormalities Structural Abnormalities

42 Structural Abnormalities Deletions: A portion of the chromosome is missing or deleted (>5 Mb). Deletions: A portion of the chromosome is missing or deleted (>5 Mb). Deletions Paraderwilli Syndrome (Ch 15) Paraderwilli Syndrome (Ch 15) Angleman Syndrome (Ch 15) Angleman Syndrome (Ch 15) Imprinting effect Imprinting effect

43 Structural Abnormalities Translocations: When a portion of one chromosome is transferred to another chromosome. Translocations: When a portion of one chromosome is transferred to another chromosome. Translocations

44 There are two main types of translocations. There are two main types of translocations. In a reciprocal translocation, segments from two different chromosomes have been exchanged. In a reciprocal translocation, segments from two different chromosomes have been exchanged.reciprocal translocationreciprocal translocation In a Robertsonian translocation, an entire chromosome has attached to another at the centromere. In a Robertsonian translocation, an entire chromosome has attached to another at the centromere.Robertsonian translocationRobertsonian translocation

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47 Chronic myelogenous leukemia (CML) 15% to 20% of leukemias in adults incidence of 1 to 2 cases per 100,000 population

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49 fluorescence in situ hybridization (FISH)

50 Autosamal Recessive Disease

51 Globin genes synthesis Lessons from the thalasemia. Nature Reviews, Genetics, volume2, 2001

52.. The human globin locus

53 Hematological values & a-Thalassemia Molecular diagnosis of hemoglobin disorders, Clin. Lab. Haem. 2004, 26, 159–176     

54 The α-globin locus is shown with the ζ- and 2 α-globin genes on chromosome 16

55 HbH Disease

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Mucopolysaccharides

58 Examples Hunter syndrome (X-L) Hunter syndrome (X-L) Hurler syndrome (AR) Hurler syndrome (AR) Scheie syndrome (AR) Scheie syndrome (AR) Sanfilippo syndrome (AR) Sanfilippo syndrome (AR) Morquio disease (AR) Morquio disease (AR) Maroteaux-Lamy syndrome (AR) Maroteaux-Lamy syndrome (AR)

59 Hurler syndrome type I ( Alpha-L-iduronate deficiency )

60 Hurler syndrome (type I)

61 Key Symptom Images Claw hand Coarse facial features Corneal clouding Hernia Mucopolysaccharidosis I (MPS I) Disease (Hurler, Hurler-Scheie, Scheie Syndromes)

62 Symptoms Short stature Short stature Full lips with a thick, large tongue Full lips with a thick, large tongue Increased body hair (hirsutism) Increased body hair (hirsutism) Deafness Deafness Stiffness (in joints) Stiffness (in joints) Shortness of breath Shortness of breath Abnormal bones of spine and claw hand Abnormal bones of spine and claw hand

63 Hunter syndrome type II (Sulpho-idoronide sulphatase deficiency )

64 Hunter syndrome type II

65 Sanfilippo syndrome type III

66 SMA SPINAL MUSCULAR ATROPHY

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68 CLASSIFICATION SMA TYPE I (Werdnig-Hoffmann) SMA TYPE I (Werdnig-Hoffmann) SMA TYPE II (Classic) SMA TYPE II (Classic) SMA TYPE III (Kugelberg-Welander) SMA TYPE III (Kugelberg-Welander)

69 OTHER CLASSIFICATION

Bone Diseases OI

71 Osteogenesis imperfecta

72 Collagens Procollagen Troprocollagen

73 X-linked Disease

74 Severity of disease Osteogenesis imperfecta: Osteogenesis imperfecta: type II> type III> type IV> type I type II> type III> type IV> type I

Hemophilia A/B

76 How is ’Hemophilia’ inherited?

DuchenneMuscular dystrophy

78 Waddling gait

79 In the late stages of muscular dystrophy: fat and connective tissue often replace muscle fibers

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81 DMD