Abstract
Methylmalonic acidemia (MMA) is a severe, heterogeneous disorder of methylmalonate and cobalamin (cbl; vitamin B12) metabolism with a poor prognosis that can cause brain damage. Identifying the magnetic resonance imaging (MRI) findings of MMA might help to make accurate diagnoses earlier in the disease course and exploring the relationship between neuropsychological scores and MRI findings, when therapy is more effective and to improve therapeutic efficacy. Cerebral MRI studies from 37 children with MMA were evaluated by a neuroradiologist. Clinical and imaging data were collected from each patient. All tests were performed during routine investigations and in accordance with the ethical principles of the Declaration of Helsinki. Informed consent was obtained from the guardians of all patients for inclusion in the study. The most common and significant findings were periventricular white matter changes (78.4%), ventricular dilation (29.7%) and cerebral atrophy (40.5%). According to the developmental quotient, the 37 patients were divided into the normal intelligence subgroup (NI, developmental quotient ≥ 85) and the low intelligence subgroup (LI, developmental quotient < 85). The incidence of corpus callosal thinning, cortical atrophy, subcortical white matter changes, and ventricular dilation (grades 0–3) was significantly higher in the LI subgroup than in the NI subgroup (P < 0.05). The incidence of no-mild and moderate-severe ventricular dilation was significantly higher in the LI subgroup than in the NI subgroup (P < 0.05). Ventricular dilatation, cerebral atrophy, white matter changes, and corpus callosal thinning are the main MRI abnormalities in MMA patients, and these manifestations are significantly correlated with delayed development in children.
Highlights
IntroductionThe mut type and the cblA, cblB, and cblH deficiency types present as MMA alone and are classified as isolated MMA; the cblC, cblD, and cblF deficiency types are classified as MMA combined with h omocysteinemia[5,6], MMA combined with homocysteinemia is the main biochemical type of MMA in China, accounting for 60–80% of cases[7], and cblC is the most common subtype[8,9]
We studied the findings in two different subgroups of MMA patients identified by newborn screening (NS) and MMA patients identified by suspected symptoms (SS): the normal intelligence (NI) subgroup and the low intelligence (LI) subgroup
Among 37 patients (27 males and 10 females), SS of MMA were found in patients, and patients underwent genetic screening after birth for genetic metabolic diseases
Summary
The mut type and the cblA, cblB, and cblH deficiency types present as MMA alone and are classified as isolated MMA; the cblC, cblD, and cblF deficiency types are classified as MMA combined with h omocysteinemia[5,6], MMA combined with homocysteinemia is the main biochemical type of MMA in China, accounting for 60–80% of cases[7], and cblC is the most common subtype[8,9]. The incidence is low, the mortality and disability rates are very high[11] This disease has diverse and nonspecific clinical manifestations,the main manifestations are feeding difficulties, intellectual disabilities, ataxia, abnormal muscle tone, convulsions, epilepsy, and lethargy[12,13]. Magnetic resonance imaging (MRI) causes no radiation damage and is suitable for brain examinations in children. This modality is increasingly used in neuroimaging studies of genetic metabolic diseases. Identifying the magnetic resonance imaging (MRI) findings of MMA might help to make accurate diagnoses earlier in the disease course and exploring the relationship between neuropsychological scores and MRI findings, when therapy is more effective and to improve therapeutic e fficacy[14]
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