3-Methylcrotonyl-Coa Carboxylase 1 Deficiency; MCC1D

What is 3-Methylcrotonyl-Coa Carboxylase 1 Deficiency; MCC1D?

3-Methylcrotonyl-Coa Carboxylase 1 Deficiency; MCC1D is a rare disease. It is also known as 3-methylcrotonylglycinuria I MCC deficiency Mcc1 Deficiency Mccd Type 1 Methylcrotonylglycinuria Type I.

The enzyme responsible for this condition takes part in the breakdown of leucine and is biotin dependent. It should be noted that some patients with this enzyme deficiency might have a deficiency of all 3 mitochondrial, biotin dependent carboxylases i.e. propioyl CoA carboxylase and pyruvate carboxylase as well as the enzyme under consideration. There is a persistent high excretion of 3-hydroxyisovalerate and 3-methylcrotonylglycine. usually combined with a secondary carnitine deficiency. Note that the enzyme is a heterodimer consisting of alpha and beta subunits
Clinically there is hypotonia and episodic metabolic acidosis. some cases might be thought to have a viral encephalitis (Chang and Larsen, 1998). Anterior horn cell disease has been reported. One case reported by Murayama et al., (1997), failed to thrive, had seizures and exhibited chronic progressive rigidity, dystonia and spasticity. She was initially thought to have cerebral palsy. The case reported by Ihara et al., (1997), was picked up on the neonatal screening programme for maple syrup urine disease. The case reported by Wiesmann et al., (1998) had partial deficiency, but died in infancy of progressive respiratory failure. Two sibs (Yap et al., 1998), had no neonatal problems , but presented with non-specific mental delay. An episode of deranged metabolism caused a stroke in the 16 month-old patient described by Steen et al., (2000), A case reported by Martin et al., (2008) had features of a connective tissue disorder.
Visser et al., (2000), commented on the clinical variability within families. The proband in their family had a cardiomyopathy, whereas her sib only had developmental delay. Their father (a carrier) seemed to have biochemical evidence of the condition!
Visser et al., (2000) reported a girl with this disorder who had a severe dilated cardiomyopathy. The cardiomyopathy was not reversed by carnitine supplementation. The 10-year-old brother had similar biochemical findings but was clinically normal. The father was also said to have similar biochemical findings and was also normal. 3-methylcrotonyl-CoA carboxylase deficiency was established enzymatically in all three cases. In general, patients do not respond to biotin, but the 2 patients reported by Baumgartner et al., (2004), did.
Both the alpha and the beta subunits of MCC have been mapped - alpha to 3q25-27 and beta to 5q12-13 (Gallardo et al., 2001). These authors have found mutations in both subunits. Further mutations in MCCA (3q26-q28) and MCCB (5q13) were reported by Holzinger et al., (2001)

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* This information is courtesy of the L M D.

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What gene changes cause 3-Methylcrotonyl-Coa Carboxylase 1 Deficiency; MCC1D?

The syndrome is inherited in the following inheritance pattern/s:

Autosomal Recessive - Autosomal recessive inheritance means an affected individual receives one copy of a mutated gene from each of their parents, giving them two copies of a mutated gene. Parents, who carry only one copy of the gene mutation will not generally show any symptoms but have a 25% chance of passing the copies of the gene mutations onto each of their children.

In some cases, a genetic syndrome may be the result of a de-novo mutation and the first case in a family. In this case, this is a new gene mutation that occurs during the reproductive process.

OMIM Number - 210200 (please check the OMIM page for updated information)

The syndrome can be caused by mutations in the following gene/s location/s:
MCCC2 - 5q13.2
MCCC1 - 3q27.1

What are the main symptoms of 3-Methylcrotonyl-Coa Carboxylase 1 Deficiency; MCC1D?

The typical symptoms of the syndrome are:
Acute hepatic steatosis, Coma, Failure to thrive, Feeding difficulties in infancy, Autosomal recessive inheritance, Seizure, Opisthotonus, Ketonuria, Lethargy, Muscular hypotonia, Intellectual disability, Hyperreflexia, Global developmental delay, Acute hyperammonemia, Hypoglycemia, Episodic metabolic acidosis, Vomiting, Phenotypic variability

How does someone get tested for 3-Methylcrotonyl-Coa Carboxylase 1 Deficiency; MCC1D?

The initial testing for 3-Methylcrotonyl-Coa Carboxylase 1 Deficiency; MCC1D can begin with facial genetic analysis screening, through the FDNA Telehealth telegenetics platform, which can identify the key markers of the syndrome and outline the type of genetic testing needed. A consultation with a genetic counselor and then a geneticist will follow.

Based on this clinical consultation with a geneticist, the different options for genetic testing will be shared and consent will be sought for further testing.

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