Merlob Syndrome

At a glance

Inherited disorder characterized by coloboma, microcephaly, porencephaly, and hydronephrosis, in which an affected individual has a circumference of the head less than three standard deviations below the age- and sex-related statistical mean. All affected individuals present severe mental retardation.

Synonyms

Primary Autosomal Recessive Microcephaly; MCPH (an acronym that stands for MicroCephaly Primary Hereditary) Syndrome.

Incidence

The exact incidence remains unknown. The prevalence is estimated at approximately 1:250,000 live births in the general population.

Genetic inheritance

True microcephaly is inherited as an autosomal recessive trait. It is genetically heterogenous, with at least five loci mapped: MCPH1 to chromosome 8p23; MCPH2 to locus 19q13.1-q13.2; MCPH3at 9q34; MCPH4at 15q15-q21; and MCPH5 to 1q31, which is a mutant of the ASPM (abnormal spindle-like, microcephaly associated) gene.

Clinical aspects

Microcephaly with sloping forehead, narrow forehead, and flat occiput. It is associated with profound mental deficiency and generalized seizures. A small but apparently normally formed brain is the reason for the reduced head circumference.

Anesthetic considerations

There are no specific considerations reported. The assessment of the severity of seizures and the medication is paramount to the success of anesthesia. It is recommended to continue the seizure medication until induction of anesthesia. One will have to consider using an intravenous antiepileptic agent intra- and in the immediate phase of the postoperative period when the patient is subjected to a long-surgical procedure, or procedure requiring significant fluid and blood administration.

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