Inborn Errors: Overview (Nursing)

00:01 In this presentation, we're going to talk about Inborn Errors of Metabolism.

00:06 And this is just going to be an overview because there are many.

00:10 So what are Inborn Errors of Metabolism.

00:14 This is a congenital condition, and it's the absence or abnormality of an enzyme, or that enzymes cofactor.

00:24 So what does that mean for our patient? We have many substances in our bodies, and many that we take in like protein, for example.

00:34 And you need enzymes or the cofactor of those enzymes to break those substances down so that our body can use them.

00:43 When these substances are not able to be broken down, because there's a deficiency of an enzyme or the cofactor, what happens is we get an accumulation of metabolites or an accumulation of those substances in the body.

00:58 And that can have really extreme consequences.

01:03 Now, sometimes, if the enzyme is missing or abnormal, we'll actually have a deficiency of the metabolites.

01:10 We don't have the substances in the body that we need for our metabolism and for general functioning.

01:18 So what causes an inborn error of metabolism? These are mostly autosomal recessive.

01:25 So this means if you remember from your genetics, that the offspring is going to inherit two copies of the gene, one from each parent.

01:33 And the genes usually come from non sex chromosomes.

01:36 And those copies must both have the condition that's going to cause the inborn error.

01:44 So there are many types of inborn errors of metabolism.

01:48 And I want to stress that you do not need to know each inborn error.

01:54 There's some broad categories of these inborn errors.

01:57 You'll see organic acidemia or amino acid disorders.

02:03 And these cause specific diseases. These also have categories.

02:08 So you might have a lysosomal storage disease.

02:12 A disease like phenylketonuria, where you have too many ketones in your body.

02:18 There's peroxisomal disorders, mitochondrial diseases, where your mitochondria just are not working correctly.

02:28 Glycogen storage diseases.

02:31 And we know if you have trouble storing glycogen that you're going to have trouble with your metabolism.

02:37 Urea cycle disorders.

02:40 So there are many different types.

02:43 So, inborn errors of metabolism can either be a single enzyme deficiency and that's the most common thing that happens or you might have abnormalities in more than one enzyme.

02:54 And when you have abnormalities in more than one, you're usually going to affect several metabolic steps.

03:02 So what does this mean for our patients? When you have a single enzyme deficiency, which is the most common, you might have an accumulation of metabolites.

03:12 An example of this would be Alkaptonuria.

03:16 And this results in an accumulation of homogentisic acid.

03:22 You might have a deficiency of metabolites as what happens in the MCAD disease, and that is going to result in an inability for the body to make keto acids.

03:35 Additionally, if you have abnormalities in more than one enzyme, as in the case of vitamin B 12 transport and synthesis, you might have an accumulation of methylmalonic acid and homocysteine.

03:49 So this affects multiple steps in the metabolism.

03:53 So how often does this happen? It turns out that the individual inborn error rates is actually pretty rare.

04:00 It's low, it's less than 100,000 live births.

04:04 But when you combine this with the fact that there are many, many different types of inborn errors of metabolism, it actually becomes a little more common.

04:13 So one in 800 to 2500 live births, depending on where you are, may have an inborn error of metabolism.

04:24 So what are patients going to look like if they have inborn errors? Well, when your metabolism is affected, it's going to include findings in almost every body system.

04:35 Primarily what we're going to notice first our problems with the neurologic system and with the gastrointestinal system.

04:43 So you might see things and especially chronic symptoms like failure to thrive and growth delay.

04:50 Maybe these patients aren't getting their developmental milestones.

04:53 They have a developmental delay, or they might even lose developmental milestones.

04:59 Infants that were able to sit up and smile at you now no longer have the ability to sit on their own.

05:05 So that's what is meant by regression of milestones.

05:09 They might experience cardiomyopathy, they might have hepatomegaly.

05:13 So their liver is really big.

05:14 You can feel it way down below their ribs.

05:17 They might have spastic diplegia, meaning that they have difficulty walking.

05:23 More acute symptoms are going to be symptoms that are consistent with shock.

05:28 So you might have dehydration.

05:30 They might be hypoglycemic, making them shaky.

05:33 They might be in a prolonged fasting state, because they just haven't been able to eat because they're nauseous, and they're vomiting.

05:41 And they are under extreme amounts of stress.

05:46 So that can progress into a metabolic emergency.

05:51 If your patient is continually vomiting, they're becoming lethargic. Maybe even falling into a coma.

05:58 Experiencing seizures, or rapid deep breathing.

06:02 That is all metabolic emergency.

06:05 Additionally, they might be breaking down their own muscles, which is rhabdomyolysis.

06:10 Might be experiencing hypothermia.

06:13 Hypothermia is often associated with more minor illness and then hyperthermia or high temperatures might follow that.

06:22 If you have a patient that has any of these symptoms that can't be explained by an illness or other condition, we have to consider the possibility of an inborn error of metabolism.

06:35 Inborn errors can really occur in any age group.

06:38 But the most severe forms are usually going to be found as a neonate.