Autosomal aberrations

Introduction Autosomal aberrations refer to diseases caused by the number of autosomes or structural abnormalities. Autosomal diseases have common clinical manifestations, such as mental retardation, growth retardation, and may be associated with abnormalities in facial features, limbs, internal organs and skin. Chromosomes in the human body are prone to changes in number and structure under certain circumstances (such as radiation), resulting in mutations or mutations that lead to chromosomal aberrations.

Cause

It is usually caused by autosomal aberrations. Chromosomes in the human body are prone to changes in number and structure under certain circumstances (such as radiation), resulting in mutations or mutations that lead to chromosomal aberrations. The most common example is the trisomy 21 syndrome, followed by the trisomy 18 syndrome, occasionally trisomy 13 , 5P-syndrome and some of the monosomy or partial trisomy abnormalities of other chromosomes.

an examination

These patients generally have more serious or obvious growth and mental retardation, with congenital multiple malformations (including special face, this face is not like their parents) and special skin lines (referring to a hand, little finger pleat, Fingerprint rectification or arching, foot and ankle and lateral arch, etc.); mainly found in infants and young children. The most common is trisomy 21, followed by trisomy 18, occasionally trisomy 13 , 5P-syndromes and some of the other monomeric or partial trisomy abnormalities.

Differential diagnosis

Differential diagnosis of autosomal aberrations:

1, 21 trisomy syndrome: also known as congenital, Down syndrome. The incidence rate of neonatal is 1/800, the ratio of male to female is 3:2, accounting for 70%-80% of pediatric chromosomal diseases. The incidence rate increases with the increase of mother's reproductive age, especially when the mother is older than 35 years old. . The karyotypes are divided into three categories: 1 standard type: 47, +21, accounting for 22.5%; 2 chimeric type: 46/47, +21, accounting for 2.7%; 2 translocation type: 46, -D, +t (Dq21q) Or 46, G, +t(Gq21q), accounting for 4.8%. About 1/4 of this type is one of the parents, which is derived from heredity. Most of the others are newly deformed. Clinical manifestations: mental retardation, IQ is 25~50; special face: low nose bridge, wide eye distance, external sacral upwards, often open mouth and tongue; sacral arch is high, head is small and round, occipital is flat, front squat is large, newborn Can have a third trick; short stature, short limbs; low muscle tone, joint relaxation; male cryptorchidism, no fertility; 50% have congenital heart disease, and may have gastrointestinal malformations, anal, cracked lips, Splitting, multi-finger, etc.; low immune function, easy to infect, prone to leukemia, often through the hand, little finger due to the second section of bone hypoplasia, wisdom and internal bending is a pleat, 10 finger ridge, sulcus, The lateral arch of the ankle and so on. 50% die within 5 years old and 8% can exceed 40 years old.

2, 18 trisomy syndrome: also known as Edwrd syndrome. The incidence rate of neonates is 1/3500~1/8000, and the ratio of male to female is 1:4. The incidence rate is related to the increase of maternal reproductive age. Karyotype: 80% is 47, +18, 10% is 46/47, +18, and the rest are various translocations. Clinical manifestations: intrauterine growth retardation, less fetal movement, and excessive amniotic fluid. Expired birth, low birth weight at birth, development as premature infants, poor sucking, weak reaction, deformity of head and face and hands and feet, head length, occipital protrusion, round face, wide eye distance, small eyeball, small mouth, narrow stenosis, ear Low, flat, upper tip, shaped like "animal ear", small jaw, short neck; loose skin, abnormal body and muscle development; special fist shape: 4th and 3rd fingers combined, index finger over the 3rd, 5th Finger over the 4th finger; rocking chair-shaped foot: male cryptorchidism; heart, lung, kidney deformity; mentally obvious defects; through the hand, the little finger a pleat. Due to the severe deformity of the child, most of them die shortly after birth, and some can live to childhood, and the chimeric type has a longer survival period.

3, 13 trisomy syndrome: also known as Patau syndrome. The incidence of neonatal is about 1 / 25,000. Karyotype: 80% is 47, 10, and the rest is translocation type. Clinical manifestations: Malformations are more severe than the upper two syndromes. Intrauterine growth retardation, birth weight, small head, small eyes or one eye, no eyes, cracked lips, cracks, heart, kidney, gastrointestinal, reproductive system malformations, mental and growth and development are seriously behind. It usually dies shortly after birth.

4, 5P - Syndrome: Also known as "Cri du chat syndrome". The population incidence rate is 1 / 500,000, accounting for 1% - 1.5% in intelligent low children, 1.3% in pediatric chromosomal diseases (Mu Ying et al, 1986), ranking first among patients with abnormal autosomal structures. Karyotype: 80% is 5P15 deletion, 10% is caused by unbalanced translocation, and some are circular chromosomes or chimeras. Clinical manifestations: Infants crying like kittens, small heads, baby full moon face, juvenile long face, wide eye distance, lateral squat, low nose, small jaw, high arch, high tooth dislocation, biting tongue; small hand and foot; Skeletal, heart, and kidney malformations; brain atrophy, decreased muscle tone in infancy, adult muscle tension hyperthyroidism; The child has slow growth and mental retardation. Most children can live in childhood, and a few can live to adulthood.

5, Prade "Willi syndrome: one of the small missing syndrome caused by a small band deletion on the chromosome, is a more common malformation syndrome. The karyotype is 15q11-q13 deletion and the missing chromosome is from the father. The child has low intelligence, short stature, obesity, low muscle tone, low gonadal development, and small hands and feet.

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