Phenylketonuria 2011

still under construction

Summary

Phenylketonuria causes several syndromes:

• Delayed mental and social skills
• Head size significantly below normal
• Hyperactivity
• Jerking movements of the arms or legs
• Mental retardation
• Seizures
• Skin rashes
• Tremors
• Unusual positioning of hands

Phenotype

The enzyme phenylalanine hydroxylase catalyzes the conversion of phenylalanie to tyrosine. If the function of phenylalanine hydroxlase is reduced by at least ... % the organism has phenylketonuria. The amount of phenylalanine in the blood rises to harming concentrations, which leads to several symptoms (see above). The more aggrevate symptoms are due to disturbances in the brain development.

Cross-references

See also description of this disease in

• Wikipedia
• OMIM
• MedScape(Genetics)
• MedScape(Dermatologic Manifestations)
• MedlinePlus
• PAHdb
• HGMD

Biochemical disease mechanism

Phenylalanine hydroxylase is involved in the phenylalanine pathway. It catalyses the conversion of phenylalanine to tyrosine. It's the major way to reduce the concentration of phenylalanine. In phenylketonuria the function of this protein is reduced by at least ... %. The missing reduction of phenylalaine leads to harmful concentrations of phenylalanine. The enzyme ... is responsible for the transport of large neutral amino acids across the blood brain barrier. Through the high concentration of phenylalanine other large neutral amino acids are less frequently transported to the brain. These missing amino acids cause severe problems in the brain development.

Cross-references

• KEGG - Phenylalanine metabolism
• MetaCyc - Phenylalanine degradation (aerobic)

Mutations

The PAH gene is a highly heterogenic locus, by now there are 642 mutations for the PAH gene known {TODO add HGMD reference}. 509 of these mutations could be associated with the disease phenylketonuria {TODO add HGMD reference}.

Mutation types

The 3 most common mutation types for the PAH gene locus are missense, deletion and splice junction mutations with 60%, 13.48% and 10.99% respectively.

Reference

pahDB mutation statistic

Gene region of mutations

After analyzing the gene regions of known mutations we found out that most mutations are located on exons of the PAH gene. The exons E7, E6, E11 and E3 contain 15.43%, 13.83%, 8.87%, 8.69% and 7.80% respectively of all mutations. In contrast, almost all introns of PAH (with only a few exceptions) contain less than 1% of all known mutations. However this seems to be somehow not surprising since more than 60% of all mutations are of type missense.

Reference

pahDB mutation statistic

Reference sequence

• reference

Neutral mutations

• Create one page per mutated sequence.

Disease causing mutations

There are 509 disease causing mutations known (HGMD).

• Create one page per mutated sequence.