<b><i>Introduction:</i></b> Trichothiodystrophy type 4 and glutaric aciduria type 3 are rare autosomal recessive disorders caused by biallelic variants in the <i>MPLKIP</i> and <i>SUGCT</i> genes on chromosome 7p14, respectively. Trichothiodystrophy type 4 is characterized by neurologic and cutaneous abnormalities. Glutaric aciduria type 3 is a rare metabolic disorder with inconsistent phenotype and elevated urinary excretion of glutaric acid. <b><i>Case Presentation:</i></b> Here, we report on an infant presenting with hypotonia, failure to thrive, microcephaly, dysmorphic features, brittle hair, hypertransaminasemia, and recurrent lower respiratory tract infections. Microarray analysis revealed a homozygous microdeletion involving the <i>MPLKIP</i> and <i>SUGCT</i> genes, which are located close to each other. <b><i>Conclusion:</i></b> Copy number variations should be considered in patients with coexisting clinical expression of different genetic alterations. To the best of our knowledge, our patient is the second case with co-occurrence of trichothiodystrophy type 4 and glutaric aciduria type 3, resulting from a contiguous gene deletion.

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