Meckel syndrome

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Meckel syndrome is an extremely rare and lethal genetic disorder, characterized by renal cystic dysplasia, central nervous system malformations, and hepatic developmental defects.

[edit] Diagnosis

Dysplastic kidneys are prevalent in 95% to 100% of all identified cases. When this occurs, microscopic cysts develop within the kidney and slowly destroy it, causing it to enlarge to 10 to 20 times its original size. The level of amniotic fluid within the womb may be significantly altered or remain normal, and a normal level of fluid should not be criteria for exclusion of diagnosis.

Occipital Cepholocele is present in 60% to 80% of all cases, and post-axial polydactyly is present in 55% to 75% of the total number of identified cases. Bowing or shortening of the limbs are also common.

Finding at least two of the three features of the classical triad, in the presence of normal karyotype, makes the diagnosis solid. Regular ultrasounds and pro-active prenatal care can usually detect symptoms early on in a pregnancy.

[edit] Genetics

This condition is inherited in an autosomal recessive pattern, meaning two copies of the gene in each cell are altered

Meckel–Gruber syndrome (MKS) is an autosomal recessive lethal malformation. Recently, two MKS genes, MKS1 and MKS3, have been identified recently. A study done recently has described the cellular, sub-cellular and functional characterization of the novel proteins, MKS1 and meckelin, encoded by these genes.[1] The malfunction of this protein production is mainly responsible for this lethal disorder.

[edit] Incidence

While not precisely known, it is estimated that the general rate of incidence, according to Dr. Bergman^[1], for Meckel syndrome is .02 per 10,000 births. According to another study done six years later, the incidence rate could vary from 0.07 to 0.7 per 10,000 births^[2].

The frequency of this syndrome is much higher in Finland, where the incidence is as high as 1.1 per 10,000 births. It is estimated that Meckel syndrome accounts for 5% of all neural tube defects there.^[3]

[edit] References

1. ^ Bergsma, D., (1979). Birth Defects. In Atlas and Compendium. National Foundation March of Dimes. The Macmillan Press Ltd.(London)
2. ^ Salonen, R., Norio, R.(1984).The Meckel syndrome: Clinicopathological Findings in 67 Patients. American Journal of Medical Genetics, 18: 671 - 689
3. ^ Nyberg, D.A., et al. (1990). Meckel – Gruber syndrome; Importance of Prenatal Diagnosis. Journal of Ultrasound Medicine, 9, 691 - 696.