Common Chromosomal and Genetic Disorders in Children

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Chromosome Abnormalities

Children with chromosome abnormalities are born with an irregular number of chromosomes (more than or fewer than 46) or with one or more chromosomes that have irregular structures (deletions from or duplications to parts of an individual chromosome, or with a part of one chromosome moved to another location).

Down Syndrome

Incidence

1 per 700-1,000 births

Characteristics^a

Children with Down syndrome have one extra chromosome. Physical characteristics include a protruding tongue, thick lips, flat nose, short neck, wide gaps between toes, short fingers, specific health problems, and risks for heart problems and hearing loss. Mental retardation can range from mild to severe. Children often have good visual discrimination skills and may be better at understanding verbal language than producing it.

Implications for Care

Provide explicit instruction in any delayed skills (e.g., in language). Address health issues such as heart problems and potential feeding difficulties.

Klinefelter Syndrome

Incidence

1 per 500-1,000 boys

Characteristics^a

Only boys have Klinefelter syndrome; they have one Y chromosome and two X chromosomes. Diagnosis may not occur until adolescence, when testes fail to enlarge. Affected boys tend to have long legs, to grow modest breast tissue, a/1d to remain sterile. They tend to show lower than average verbal ability and some speech and language delays.

Implications for Care

Offer an enriched verbal environment. Medical treatment may be given to support development of male sexual characteristics.

Turner Syndrome

Incidence

1 per 2,500-5,000 girls

Characteristics^a

Only girls have Turner syndrome; they have one X chromosome and are missing the second sex chromosome. Affected girls have broad chests, webbed necks, short stature, and specific health problems. They do not show normal sexual development. They may show normal verbal ability but lower than average ability in processing visual and spatial information.

Implications for Care

Provide instruction and support related to visual and spatial processing. Hormone therapy helps with bone growth and development of female characteristics.

Prader-Willi Syndrome

Incidence

1 per 10,000-25,000 births

Characteristics^a

A deletion from a gene segment on chromosome 15 is inherited from the father. Children with this syndrome tend to become obese and show mental retardation; they also have small hands and feet and are short in stature. They may develop maladaptive behaviors such as throwing frequent temper tantrums and picking at their own skin. Beginning at ages 1-6, children may eat excessively, hoard food, and eat unappealing substances.

Implications for Care

Create developmentally appropriate plans to help children regulate eating, decrease inappropriate behaviors, and increase acceptable emotional expression. Seek medical care as necessary.

Angelman Syndrome

Incidence

1 per 10,000-30,000 births

Characteristics^a

A deletion from a gene segment on chromosome 1 5 is inherited from the mother. Children with this syndrome show mental retardation, a small head, seizures, and jerky movements. They have unusual, recurrent bouts of laughter not associated with happiness.