Microcephalic primordial dwarfism with predominant Meier–Gorlin phenotype, ichthyosis, and multiple joint deformities—Further expansion of DONSON Cell Cycle‐opathy phenotypic spectrum

We report a patient with microcephalic primordial dwarfism with predominant Meier–Gorlin syndrome phenotype with ichthyosis and disabling multiple joint deformities in addition to classic features of the syndrome. The patient was a 10.5‐year‐old girl referred in view of short stature, joint deformities, and facial dysmorphism. There was history of intrauterine growth restriction and collodion like skin abnormality at birth. She had normal developmental milestones and intellect. On clinical evaluation, anthropometry was suggestive of proportionate short stature and microcephaly. There was abnormal posture due to spine and peripheral joint deformities, along with ichthyosis, facial, and digital dysmorphism. Skeletal radiographs showed radial subluxation, acetabular dysplasia and hip dislocation, bilateral knee joint dislocation, absent patellae, slender long bones with delayed bone age, and subluxation of small joints of hands and feet. Work up for metabolic bone disease and peripheral blood karyotype was normal. Whole exome sequencing revealed a pathogenic homozygous variant c.C1297T (p.Pro433Ser) in the exon 8 of DONSON gene. This report further expands the genotypic–phenotypic spectrum of the group of disorders known as Cell Cycle‐opathies.