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3-Methylcrotonyl-Coa Carboxylase 1 Deficiency; MCC1D

3-Methylcrotonyl-Coa Carboxylase 1 Deficiency; MCC1D

OMIM number: 210200

Comments closing date: 02/02/2023

3-methylcrotonyl-CoA carboxylase deficiency is an
inherited disorder in which the body is unable to
process certain proteins properly. People with this
disorder have a shortage of an enzyme that helps
break down proteins containing a particular
building block (amino acid) called leucine. Infants
with 3-MCC deficiency appear normal at birth but
usually develop signs and symptoms in infancy or
early childhood. The characteristic features of this
condition, which can range from mild to life threatening, include feeding difficulties, recurrent
episodes of vomiting and diarrhoea, excessive
tiredness (lethargy), and weak muscle tone
(hypotonia). If untreated, this disorder can lead to
delayed development, seizures, and coma. Many
of these complications can be prevented with early
detection and lifelong management with a low protein diet and appropriate supplements. Some
people with gene mutations that cause 3-MCC
deficiency never experience any signs or
symptoms of the condition.

Review date: 5 January 2025