Prenatal Diagnosis of Bardet-Biedl Syndrome: A Case Study and Review of Literature

Abstract

AbstractBardet-Biedl syndrome (BBS) is a rare autosomal recessive disease with a prevalence rate of 1 in 125,000–170,000. BBS can occur as a result of mutation in one of the 19 known genes of the BBS gene complex. The syndrome is mostly diagnosed post-natally based on the structural and functional manifestations of the disease in childhood like short stature, obesity, polydactyly or syndactyly, retinal dystrophy, structural renal abnormalities, neurodevelopment delays, mental retardation, diabetes mellitus. We present a case of Bardet-Biedl syndrome diagnosed prenatally at 18 weeks gestation based on prenatal ultrasound findings of post axial polydactyly with bilateral hyperechogenic kidneys. Clinical suspicion based on ultrasound findings was supplemented amniocentesis and clinical exome sequencing. This showed a pathogenic variant in homozygous state in the MKKS gene, consistent with Bardet-Biedl syndrome type 6. Unless BBS has been suspected antenatally, diagnosis of BBS is usually made in late childhood or early adulthood adding to the psychological, emotional and financial burden on the family. With advances in prenatal ultrasound techniques and tremendous improvement in genetic diagnosis of suspicious findings on ultrasonography, diagnosis of rare genetic disorders like BBS is now possible as early as the 18–20 weeks scan. This can aid in appropriate counseling of the family and timely intervention in children born with this condition.