Chromosomal Disorders

Chromosomal abnormalities are fairly common. They occur in about 1 in every 200 deliveries, although many of these infants are phenotypically normal. In addition, 50% of all spontaneous abortions involve a chromosomal abnormality. Nondisjunction, where an extra chromosome (or part of a chromosome) is present (e.g., trisomy 21), is the most common cause of chromosomal disorders. Translocation syndromes, where chromosomal material breaks off from one chromosome and translocates to another, may not have classic clinical findings and may be difficult to diagnose. Usually infants with balanced translocations are only carriers and do not demonstrate clinical manifestations, while unbalanced translocations result in clinical signs. A deletion occurs when chromosomal material is missing from either the upper (p) or lower (q) arms of a chromosome (e.g., cri du chat syndrome with deletion of the upper short arm of chromosome 5 5p-). An abnormal number of X or Y chromosomes can also result in significant clinical syndromes (e.g., Turner's syndrome with absence of one of the X chromosomes 45X0). Chromosomal analysis should be considered for all stillbirths, newborns with multiple congenital anomalies, or to confirm a suspected chromosomal diagnosis.

Wolf Hirschhorn

Figure 4.1. In the syndrome caused by deletion of the short arm of chromosome number 4 Hp-syndrome, Wolf-Hirschhorn syndrome), there is marked prenatal growth deficiency and decreased fetal activity. At birth the facial features are typical: microcephaly, a high forehead, prominent glabella, and a wide nasal bridge with nasal beaking (the "Grecian helmet" appearance of the head). This infant also has craniofacial asymmetry.

Figure 4.1. In the syndrome caused by deletion of the short arm of chromosome number 4 Hp-syndrome, Wolf-Hirschhorn syndrome), there is marked prenatal growth deficiency and decreased fetal activity. At birth the facial features are typical: microcephaly, a high forehead, prominent glabella, and a wide nasal bridge with nasal beaking (the "Grecian helmet" appearance of the head). This infant also has craniofacial asymmetry.

Figure 4.2. A frontal view of the same infant shows the high forehead and a prominent glabella. The eyebrows are highly arched and sparse medially. There is nasal beaking and epicanthic folds with bilateral ptosis. There is a short deep philtrum with a short upper lip and a turned-down, fish-like mouth. A cleft lip and/or palate occurs in about 10% of these infants.

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Responses

  • Juuso
    What causes wolf hirschhorn syndrome?
    3 months ago

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