(Cytogenetics)Mendelian Disorders
Congenital malformations
Ehlers-Danlos syndromes(EDS)
mosaicism for trisomic and normal cells
Partial Trisomy (duplication): 1q, 13q, 9p, 4p, 10q,
11q, 7q, 14q, 1q, 3p, 4q, 8q, 10p, 11p, 15q, 20p
Monosomy: 21, 22
18q, 11q, 7p, 9p, 12p
Polyploidy : Triploidy, Tetraploidy
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Translocation type
Mental retardation, Flat facial profile, Oblique palpabral fissure, Muscle hypotonia, Hyperflexibility, Lack of Moro reflex, Abundant neck skin, Broad and short trunk, Dysplastic ears, Horizontal palmar crease, Dysplastic pelvis,
Dysplastic middle pharynx, Epicanthic folds, Acute leukemias
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Wide “sandal” gap
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Prominent epicanthal fold
Translocation 46,XX,der(Dq;13q),+13 10%
Clinical Features (1 in 6000 births)
Microcephaly and mental retardation, Scalp defect, Microphthalmia, Cleft palate, Polydactyly,
Rocket-botton feet, Abnormal ears,
Cardiac dextroposition and VSD,
cleft palate, atrial septal defect, inguinal hernia, and postaxial polydactyly of the left hand.
polydactyly, particularly of all extremities, strongly suggests trisomy 13.
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Translocation type
Clinical feature (1 in 5000 births)
Mental retardation, failure to thrive,
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low-set ears, hypertonicity,
short sternum and
small face, micrognathia
Karyotype : 46,XX,5p- 46,XY,5p-
Maternal age : Normal
Maternal age : Normal
Most are stillborn or die in infancy
wide-spaced eyes and repaired cleft lip
chromosome deletion 4p syndrome,
WHSC1=Wolf-Hirschhorn syndrome candidate 1
Translocation of 4p ------ 13%
hypotonia, hypogonadism, and obesity
age of onset: newborn
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hyperphagia and obesity, dysmorphic face, hypopigmentation,
intellectual disability, short status
dysmorphic face, happy and puppet syndrome, easily provoked laughter
3) others : Imprinting defects
Prader-Willi syndrome (del 15q11.2-q13)
Angelman syndrome (del 15q11-q13)
Williams syndrome (del 7q11.23)
Langer-Giedion syndrome (del 8q24)
Smith-Magenis syndrome (del 17p11.2)
Incidence : rare
Varying genital abnormalities
Karytype : 47,XYY
Clinical features : Phenotypically normal, Most over 6 feet tall,
Increased aggressive behavior(?)
Karytype : 47,XXX 48,XXXX
Many normal and fertile
Karyotyoe 47,XXY (classic) 46,XY/47,XXY
Turner Syndrome (Gonadal Dysgenesis)
46,XXp- 46,XXq- 46,X,r(X)
Webbing of neck, Cubitus valgus, Peripheral lymphedema,
Broad chest & wide-spread nipples
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Fragile X Syndrome
Incidence : about 1 in 1500 males. Affected female carriers are typically normal.
Most of the affected males have mental retardation, and their testes are larger than normal.
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SEX REVERSAL
21-hydroxylase deficiency
17-hydroxyprogesterone
: 46,XX
- due to deletion of X-linked androgen receptor gene
Pseudohermaphroditism ()