Congenital fibrosis of the extraocular muscles type 2, an inherited exotropic strabismus fixus, maps to distal 11q13

Article Abstract:

Congenital fibrosis of the extraocular muscles type 2 maps to distal 11q13. It is an inherited exotropic strabismus fixus. The extraocular fibrosis syndromes are congenital ocular-motility disorders. They come from dysfunction of the oculomotor, trochlear and abducens nerves and or the muscles they innervate and each has certain form of restrictive paralytic ophthalmoplegia with/without ptosis. In the classic form of congenital fibrosis of the extraocular muscles (CFEOM1) the children are born with a restrictive infraductive external opthalmoplegia and bilateral ptosis. Exotropic strabismus fixus is a variant of CFEOM. Genetic analysis involved 70 people, 20 of them affected. Two of the three families have a common disease-associated haplotype. It appears that CFEOM2 has a founder effect.

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HMG CoA lyase deficiency: identification of five causal point mutations in codons 41 and 42, including a frequent Saudi Arabian mutation, R41Q

Article Abstract:

Hereditary deficiency of 3-hydroxy-3-methylglutaryl (HMG) CoA lyase (HL) brings with it episodes of hypoketotic hypoglycemia and coma. It shows up frequently and is clinically severe in Saudi Arabia. In nine Saudi HL-deficient probands genetic diversity was found. Six were homozygous for the missense mutation R41Q. Two were homozygous for the frameshift mutation F305fs(-2). In 32 probands that were non-Saudi and HL-deficient, three R41Q alleles were found. There are four other point damaging mutations in codons 41 and 42, which are important for normal HL catalysis. They account for 21 of 82 mutant alleles in the group of HL-deficient probands.

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The haptoglobin-gene deletion responsible for anhaptoglobinemia

Article Abstract:

An allelic deletion of the haptoglobin (Hp) gene has been found for a person with anhaptoglobinemia. The mechanisms of anhaptoglobinemia and that of anomalous inheritance of Hp phenotypes can be explained on the basis of the study. The mechanism of hypohaptoglobinemia is not known. The homozygous gene deletion of the Hp gene cluster occurs in the person with anhaptoglobinema and the heterozygous gene deletion is seen in those with hypohaptoglobinemia.

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