Unusual context of variants and primary microcephaly: compound heterozygosity and nonconsanguinity in an Argentinian patient.

Primary microcephaly (MCPH) is a genetically heterogeneous disorder showing an autosomal recessive mode of inheritance. Patients with MCPH present head circumference values two or three standard deviations (SDs) significantly below the mean for age- and sex-matched populations. MCPH is associated with a nonprogressive mild to severe intellectual disability, with normal brain structure in most patients, or with a small brain and gyri without visceral malformations. We present the case of an adult patient born from Argentinian nonconsanguineous healthy parents. He had a head circumference >5 SD below the mean, cerebral neuroimaging showing hypoplasia of the corpus callosum, bilateral migration disorder with heterotopia of the sylvian fissure and colpocephaly. The patient was compound heterozygous for pathogenic variants in the gene (c.289dupA inherited from his mother and c.1132 C > T inherited from his father). Our patient represents an uncommon situation for the usual known context of and MCPH, including family origin (Argentinian), pedigree (nonconsanguineous), and genotype (a compound heterozygous case with two variants predicting a truncated protein). Next-generation sequencing studies applied in a broader spectrum of clinical presentations of MCPH syndromes may discover additional similar patients and families.