Tryptophan Hydroxylase Deficiency
Description
Tryptophan Hydroxylase Deficiency (TPHD) is a rare genetic disorder that disrupts the production of serotonin, a crucial neurotransmitter impacting mood, sleep, appetite, and other bodily functions. This blog delves into the intricacies of TPHD, covering its signs and symptoms, underlying causes, inheritance patterns, diagnostic methods, management strategies, and insights into living a fulfilling life with this condition.
Genes Involved
Tryptophan hydroxylase deficiency arises from mutations in the TPH1 gene, located on chromosome 11. This gene provides instructions for producing the enzyme tryptophan hydroxylase 1, which plays a crucial role in the first step of serotonin synthesis. Mutations in the TPH1 gene can impair or completely block the enzyme‘s function, leading to serotonin deficiency.
Recognizing the Signs and Symptoms
TPHD presents a wide spectrum of symptoms, often appearing during infancy or early childhood. Common signs include:
- Irritability and crying: Infants with TPHD may exhibit excessive crying and difficulty calming down.
- Feeding problems: Poor feeding, failure to thrive, and vomiting are common.
- Sleep disturbances: Sleep difficulties, including frequent awakenings and insomnia, can be significant.
- Delayed development: Developmental delays in motor skills, language, and cognitive function may occur.
- Movement disorders: Some individuals may experience involuntary movements or tremors.
- Seizures: In severe cases, seizures can arise.
It‘s important to note that symptoms can vary greatly between individuals.
Causes
TPHD is caused by inherited mutations in the TPH1 gene. These mutations are passed down from parents to their children, following an autosomal recessive inheritance pattern. This means that an individual must inherit two copies of the mutated gene, one from each parent, to develop the disorder. If an individual inherits only one copy of the mutated gene, they are considered a carrier and do not typically exhibit symptoms but can pass the gene on to their children.
Inheritance/recurrence risk
TPHD follows an autosomal recessive inheritance pattern, meaning both parents must carry the mutated TPH1 gene for their child to inherit the disorder. If both parents are carriers, there is a 25% chance their child will inherit TPHD, a 50% chance their child will be a carrier, and a 25% chance their child will inherit two normal copies of the gene. If only one parent is a carrier, there is no risk of their child developing TPHD but a 50% chance their child will become a carrier.
