In Microcephaly there is a defect in the growth of the brain which causes it to be smaller than the normal brain. Microcephaly can be detected by measuring the head circumference. Detailed X-ray examination (CT Scan) may demonstrate an alteration in the normal brain structure, for example, a decrease in the number of the complexity of the folds on the surface of the brain. More frequently, the CT scan appearance simply confirms reduction in brain size.

Microcephaly may be caused by different conditions both genetic and non-genetic in origin. For example, genetic causes include different chromosome disorders, different single gene abnormailities and specific genetic syndromes. Non-genetic causes include infections contracted by the baby in the womb (intrauterine infections), reduction in blood supply to the developing fetal brain during pregnancy and some post-natal infections. Intrauterine infections which can cause Microcephaly include cytomegalovirus (CMV), toxoplasmosis and rubella (German measles).

Rare syndromes which cause disturbed brain development and Microcephaly, usually with other physical handicaps, include Cornelia DeLange Syndrome, Rubinstein Tayabi and Seckel syndrome.

Inheritance Patterns:   Different inheritance patterns of genetic Microcephaly are possible: In autosomal dominant Microcephaly, one affected parent has 50% chance of transmitting the gene fault to each child they have. In autosomal recessive Microcephaly both parents are unaffected but carry a Microcephaly gene and there is a 25% chance that each child they have will be affected by Microcephaly. In X-chromosome linked Microcephaly, an unaffected mother who carries an X-chromosome linked Microcephaly gene has 25% chance of a son affected by Microcephaly. Of these three different inheritance mechanisms, autosomal recessive Microcephaly is probably the most common.

Pre-Natal Diagnosis: It is unusual for genetic Microcephaly to be diagnosed in early pregnancy because the various gene defects which may possibly underly genetic Microcephaly remain unknown and pre-natal ultrasound scanning rarely reveals reduced head growth before the last five months of pregnancy.

Further information available from:

Mrs Jacqui Smith,
Microcephaly support group
22 Auctioneers Court
The Old Cattlemarket
Northampton
NN1 1EY
(Tel: 01604 603743)

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The Microcephaly support group was re-organised in 1992 with the assistance of Contact a Family. It offers:

• Support for families through an area family network
• Family link service
• Information on the condition
• 24 hour emergency contact line

Activities:

• Annual National conference with guest speaker

The group has approximately 200 members.