Schaaf-Yang syndrome (SYS): a case report

*Correspondence: [e-mail].

Abstract

Case Presentation: Male, born at term in need of neonatal resuscitation, being referred to the NICU without ventilatory support. In the neonatal period dysmorphic features were noted such as: broad-based nostrils, long eyelashes, bilateral cryptorchidism and hydronephrosis. Pacient had deficits in sucking, swallowing and gastroesophageal reflux confirmed with barium esophagram, being submitted to gastrotomy with fundoplication at 4 months, when he was discharged from the maternity ward. At 8 months, diagnosed with severe malnutrition, hypoglycemia and irritability. On neurological examination, was observed axial hypotonia with joint contractions of the upper limbs and opisthotonus. He maintained recurrent episodes of hypoglycemia and failure to thrive. Screening for inborn errors of metabolism was performed, without alterations. Evaluated by pediatric endocrinology team which identified hypocortisolism and GH deficiency. Brain MRI was performed, which showed cystic leukomalacia in the occipital region compatible with neonatal distress. When clinical Exoma was performed, a probably pathogenic variant (c.1996C>T/p.(gln666*)) was found in heterozygosis in the MAGEL2 gene, associated with Schaaf-Yang Syndrome (SYS).

Discussion: SYS is an ultra-rare syndrome, characterized by neurodevelopmental delay, behavioral disorders, congenital hypotonia, distal joint contractures, respiratory abnormalities, body temperature instability, and gastrointestinal problems mainly related to feeding, which often may result in the need for temporary or permanent alternative feeding routes, as described in the case (1,2). Endocrinological alterations, such as hypopituitarism and GH deficiency may be present, as in the reported case. Among the endocrinopathies described in the SYS, it is possible to highlight the abnormalities in glucose metabolism, which course with hypoglycemia, as also presented by the patient (3).

Final Comments: SYS is a multisystem disease, with hormonal variation and glucose metabolism, but the diagnosis is based on the identification of a pathogenic/probably pathogenic variant in the Exoma or genome. We highlighted the great variability of phenotypes associated with congenital hypotonia, diagnosed from the new generation sequencing tests, and the need to implement this test in the SUS, for a quick diagnosis and early therapeutic procedures, aiming to minimize the risk of complications and sequelae.

Publication History

Article published online:
12 May 2025