Trisomy 5p

Complete trisomy 5p is a rare chromosomal disorder in which the short arm of chromosome 5 is duplicated, resulting in a distinct clinical syndrome. According to Kim et al., only 12 cases of complete trisomy 5p were reported in the literature, 2 of which were prenatal. The authors present the most comprehensive review of complete trisomy 5p to date, compiling data from their 3 new cases with prior cases in the literature to organize clinical features and provide guidance for medical management in the absence of published guidelines. Participants were recruited via a patient support group on Facebook, resulting in 3 new patients with confirmed complete trisomy 5p. The authors also conducted a literature review to investigate clinical presentations, diagnoses, and medical interventions in those with trisomy 5p. The most common features noted among all cases were neonatal hypotonia, talipes equinovarus, dysmorphic facial features, and macrocephaly. More novel features identified in this study include malformation of the eye, short umbilical cord, imperforate anus, and intestinal malrotation. The following symptoms are also associated with the condition: seizures, developmental delay, respiratory infections, failure to thrive, musculoskeletal abnormalities, dysmorphic ears and feet, congenital heart defects, and abnormalities of the brain. Diagnosed patients often have a normal birth weight and length, followed by postnatal growth failure. The condition is unfortunately associated with high mortality, often due to respiratory complications. Based on the findings of this study, the authors recommend the following in light of a lack of published guidelines: echocardiogram; baseline renal ultrasound; ophthalmology and audiology referrals; otolaryngology consultation and swallow study; early intervention programs for developmental delay; careful observation of feeding and growth with consideration of a nasogastric or gastrostomy tube; neuroimaging; musculoskeletal examination; and educating families and patients on the signs and symptoms of seizures. The authors discuss the potential of 5p13 as a critical region for the manifestation of facial dysmorphisms, eye abnormalities, macrocephaly, and cerebral malformations. This is supported in previous literature in which patients with duplications in 5p13 exhibit similar features to those with complete trisomy 5p. Duplication of 5p11 has additionally been associated with failure to thrive, talipes equinovarus, and anorectal malformations. Multiple underlying mechanisms of the condition have been suggested, such as an isochromosome of 5p and a translocation involving 5q to another chromosome. Although many cases of trisomy 5p are de novo, some occur when parents are carriers of the condition (particularly with translocations), as was the case in 1 of the 3 new cases presented by Kim et al. Consequently, the authors recommend that the parents of individuals diagnosed with trisomy 5p pursue genetic counseling and consider testing. While Kim et al. provided the most comprehensive review of the condition to date, more research must be conducted to continue to characterize the clinical syndrome, improve seizure management, and to understand immunologic phenotype and its potential role in recurrent respiratory infection.

Kim et al. “Trisomy 5p: Long Recognized, Rarely Published- Three New Cases and Review of the Literature” . “American Journal of Medical Genetics Part A” 2025, Advance online publication.