Pathogenic variants in the OFD1 gene are linked to a spectrum of syndromes that exhibit partial clinical overlap. Hemizygous loss-of-function variants are considered lethal in males, while heterozygous loss-of-function variants generally result in oro-facial-digital syndrome type 1. A reported phenotype, Simpson-Golabi-Behmel syndrome type 2, was published once but remains controversial, with many specialists questioning its validity and arguing about its continued listing in the OMIM database. To investigate the genetic and phenotypic characteristics of the patients, we performed clinical exome sequencing, family-based genetic analysis, X-inactivation studies, electron microscopy, and detailed clinical assessments. Three patients from unrelated families carrying loss-of-function variants in the OFD1 gene were identified, emphasizing the diverse phenotypic spectrum of OFD1-associated disorders. The first patient, a female with a heterozygous frameshift variant p.(Gln398LeufsTer2), was diagnosed with oro-facial-digital syndrome type 1. The second patient, a male with a heterozygous nonsense variant p.(Gln892Ter), presented with features resembling Simpson-Golabi-Behmel syndrome type 2, as previously reported under this diagnosis. The third patient, a male with another heterozygous nonsense variant p.(Glu879Ter), exhibited isolated primary ciliary dyskinesia without any syndromic features. This study contributes to the growing body of evidence on the expanding phenotypic spectrum of OFD1-associated disorders. It underscores the need for further investigation into the molecular mechanisms underlying the diverse presentations and the necessity of re-evaluating diagnostic classifications for conditions such as SGBS2 in the context of variants in the OFD1 gene.

Orofaciodigital syndrome type 1 (OFDS1) is a genetic disorder characterized by specific oral, facial, and limb malformations. A 14-month-old girl with congenital cleft palate, lower lip midline cleft, and digital anomalies admitted to our hospital was preliminarily diagnosed with OFDS1. Genetic analysis revealed that she carried a heterozygous variant of OFD1 at locus Xp22.2 on the X chromosome. Herein, we present the specific phenotype and genotype and the treatment modalities for this patient and references for diagnosing and treating OFDS.

Pathogenic variants in the OFD1 gene have been classically associated with the Orofaciodigital syndrome type 1 in females, a condition previously considered to be X-linked dominant with male embryonic lethality. However, an increasing number of males with pathogenic OFD1 variants who survived beyond the neonatal period have now been reported in the literature. Although each new report has added to the ever-broadening spectrum of clinical findings seen in males, many questions about genotype-phenotype correlations and disease mechanism remain. Herein, we describe a 9-year-old male child with a novel hemizygous pathogenic OFD1 variant identified by exome sequencing and a unique combination of findings, not previously reported, including presence of both a hypothalamic hamartoma and the molar tooth sign. His clinical features overlap multiple ciliopathy phenotypes, blurring the boundaries of distinct ciliopathy gene-disease relationships. This case provides further evidence for the consideration of a broad OFD1-relateddisorder spectrum in affected males rather than multiple distinct phenotypes. Additionally, a review of previously published cases of the disorder in males support the inclusion of the OFD1 gene in the differential diagnosis and work up for all individuals who present with primary ciliopathy-type features, regardless of their gender. We also highlight current information about OFD1 variant types and pathogenesis and explore how these could mechanistically drive some of the observed phenotypic differences.

We report the successful treatment of multiple facial milia with manual extraction and tretinoin in a child with orofaciodigital syndrome type 1. Treatment with topical medications may be insufficient in individuals with orofaciodigital syndrome type 1, and pitted scarring is often a sequala. This case demonstrates that manual extraction is well tolerated and effective in the treatment of multiple milia. In addition, clinicians need to be aware of this rare genetic condition, which commonly presents de novo and can lead to significant morbidity if untreated.