The Phenylalanine Hydroxylase
(PAH) gene, being 90-100 kb, is embedded in the genomic location 102, 836, 885-102, 958, 410, on the chromosomal region 12q23.2 (1).
We believe that the refractory hypercalcemia in this patient was due to elevated calcitriol levels due to a PTHrP-independent mechanism, possibly from either ectopic production of calcitriol in tumor cells or from increased activity of 1-alpha hydroxylase
in the same cells or alveolar macrophages.
Most of these cases were 21 hydroxylase
deficient, and only 2previous cases of 17 hydroxylase
deficiency with a myelolipoma have been previously reported.
Congenital adrenal hyperplasia due to 21- hydroxylase
Given that tyrosine hydroxylase
is the rate-limiting step in catecholamine synthesis, staining for tyrosine hydroxylase
will be supportive of the diagnosis.
Dr Vaishakhi Rustagi, Consultant, Paediatric Endocrinology, Max Super Speciality Hospital, says, "Deficiency of 21- hydroxylase
enzyme affects one in 4,000 to 6,000 people in India.
Also, uric acid inhibits expression of 1-alpha hydroxylase
protein, and higher uric acid levels are associated with higher levels of parathyroid
Ames demonstrated that vitamin D hormone activates the gene that makes the enzyme tryptophan hydroxylase
2 (TPH2), which converts the essential amino acid tryptophan into serotonin in the brain.
220.127.116.11, E20M) is the insect cytochrome P450-dependent steroid hydroxylase
responsible for the conversion of the arthropod molting hormone ecdysone (E) to its more active metabolite, namely, 20-hydroxyecdysone (20E) [1, 2].
Of special interest to the researchers were: 1) the mice's locomotor activity in response to cocaine; 2) the degree of conditioning for place preference; 3) electrical activity of the ventral tegmental area (part of the brain's reward system; it plays a role in sense of euphoria and well-being); 4) the presence of tyrosine hydroxylase
in the VTA; and 5) the presence of deoxyribonucleic acid (DNA) sequences for the Clock gene in the brain.
Bilobalide, a component of GBE that markedly induced hepatic CYPs including (S)-warfarin hydroxylase
, showed similar effects.
BH4 is required by tryptophan hydroxylase
for serotonin synthesis and by tyrosine hydroxylase
for dopamine and norepinephrine synthesis.