Learning difficulties

Usually sporadic but can be autosomal dominant (Ch 9,11,16)

Skin changes (adenoma sebaceum, shagreen patches, ash leaf spots), seizures, cortical tubers, subependymal giant cell astrocytoma, retinal hamartoma, renal angiomyolipoma, cardiac rhabdomyoma

Trisomy 21 due to non-dysjunction, translocation, mosaicism

Facial appearance, simian crease, clinodactyly, congenital heart defects, GI defects, atlantoaxial instability, dementia, thyroid disorders, diabetes, sleep apnea, hearing loss, visual problems

X-linked defect of methyl CpG-binding protein 2

Most boys die before birth. Girls: developmental retardation, mutism, movement disorder, loss of language skills, effective eye contact, as well as purposeful hand movement. Stereotypic hand movements develop (hand wringing, tapping, patting, and at times hand-mouth movements). Seizures may occur

Chromosome 5 deletion

High pitched cry, microcephaly, hypotonia, facial features (hypertelorism), low-set ears, small jaw, rounded face, congenital heart defect

Usually autosomal dominant. May be sporadic (Ch 17, 22)

Numerous benign neurofibromas, brain tumors, meningioma, schwannoma, childhood leukemia

70% sporadic (deletion on Ch 15 of paternal origin)

Inheriting the deletion through the mother gives rise to Angelman syndrome, which is characterized by short stature, severe mental retardation, spasticity, seizures and a characteristic stance. Inheriting the deletion from the father produces the more common Pader-Willi syndrome, which is characterized by obesity, excessive and indiscriminate gorging, small hands, feet, hypogonadism and mental retardation. In rare cases, uniparental disomy involving chromosome 15 produces PWS and AS when both copies are inherited from the mother and AS when both copies are inherited from the father.

Usually sporadic, may be autosomal dominant (microdeletion Ch 22)

Thymus abnormalities, ear deformities, cleft palate, cardiac defects and short stature. Hypocalcemia in adolescence

X-linked (FMR-1 gene has expansion of trinucleotide repeats at fragile site on X chromosome). Shows anticipation.

Boys with syndrome have long faces, prominent jaws, large ears, and are likely to be mentally retarded. Affected men have large ears, a high-arched palate, hypotelorism, and large testes. Autism also occurs among affected men

Deletion in Chromosome 7

Characteristic elfin facies, short stature, cardiovascular defects, dental problems and GI disorders (among others). Hypercalcemia