Health complications increase with age in Bardet-Biedl syndrome
Review of Mayo Clinic records compared children and adults with disorder
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Adults with Bardet-Biedl syndrome carry a higher burden of metabolic, hormonal, kidney, heart, and vision complications than children, according to a review of medical records at the Mayo Clinic. (Photo by iStock)
Adults with Bardet-Biedl syndrome (BBS) carry a substantially higher burden of metabolic, hormonal, kidney, heart, and vision complications than children, according to a review of medical records at the Mayo Clinic.
“Early recognition, proactive … surveillance, and comprehensive multidisciplinary care are essential to optimize management across the lifespan,” researchers wrote.
The study, “Clinical, Genetic, and Endocrine Features of Bardet-Biedl Syndrome in a Pediatric and Adult Cohort,” was published in the American Journal of Medical Genetics Part A.
Mutation in BBS1 gene the most common cause among participants
BBS is an inherited disorder characterized by a wide range of highly variable symptoms that can appear at any age. The six primary features in BBS are obesity, vision problems, learning or cognitive impairment, kidney impairment, genital anomalies, and extra fingers or toes at birth (polydactyly).
A diagnosis is typically made when a patient has at least four of those six primary features or three primary features plus at least two secondary features.
However, data on the clinical manifestations and coexisting conditions in BBS, particularly in children and adolescents, are limited.
To help inform evidence-based clinical management of BBS, a team at the Mayo Clinic in Minnesota reviewed the medical records of 31 people (seven children and 24 adults) with BBS, ages birth to 50. The median age at diagnosis was 8 years, and about half were girls/women (55%).
Among the 25 patients who underwent genetic testing, the most common cause was a mutation in the BBS1 gene (36%), followed by mutations in the BBS10 (24%), BBS2 (16%), and BBS7 genes (12%). Variants in three other genes, BBS4, IFT172, and SCLT1, were each found in a single patient (4%).
Eye disease affected nearly all adults, most children
Eye disease was one of the most consistent findings across the group. Retinal dystrophy, a progressive breakdown of the light-sensing cells at the back of the eye, affected nearly all adults (96%) and most children (71%). Among those with confirmed retinal dystrophy, two-thirds (64%) met the criteria for legal blindness based on their best-seeing eye.
Obesity was present in most children (86%) and all adults (100%). Hyperphagia, or extreme hunger, was subjectively reported in 11 patients (35%), including four children and seven adults. While no children had prediabetes or diabetes, 8% of adults had prediabetes and 38% had type 2 diabetes.
Abnormal levels of fatty molecules in the blood affected 29% of children and 46% of adults, with elevated levels of triglycerides, a fatty molecule, as the most common abnormality in both groups.
Rates of metabolic dysfunction-associated steatotic liver disease, formerly known as fatty liver disease, were similar between children and adults (29% vs. 33%).
Obstructive sleep apnea, in which the airways are repeatedly blocked during sleep, affected 14% of children and 46% of adults, while polydactyly was present in all children (100%) and most adults (75%).
These results underscore the importance of early diagnosis and longitudinal multidisciplinary care to address the progressive and [variable] nature of this disorder.
About half (46%) of adults with BBS had cardiovascular involvement compared with two children (29%). Likewise, nearly five times as many adults had high blood pressure as children (67% vs. 14%).
Chronic kidney disease was identified in 29% of children and 63% of adults, with some patients requiring dialysis, a kidney replacement treatment (6%), or kidney transplant (19%). Structural defects of the urinary and reproductive systems were observed in all children (100%) and nearly all adults (92%).
Hormone-related conditions were most common in the adult group. No pediatric patients had hypothyroidism (low thyroid hormone levels), whereas 25% of adults did. Polyendocrine metabolic ovarian syndrome, a hormonal condition formerly known polycystic ovary syndrome, was diagnosed in 21% of women.
Hypogonadism (little or no sex hormones) was identified in two adults (8%) but no children. One child was diagnosed with central precocious puberty, or early puberty. No cases of growth hormone deficiency were identified.
Neurodevelopmental and mental health conditions were common across both age groups. Learning disabilities were documented in most (71%) of children and about half (54%) of adults. Attention-deficit/hyperactivity disorder was identified in one-fifth (19%) of the total group, including one child and five adults, while anxiety and depressive disorders were present in half (52%), including one child and fifteen adults.
“These results underscore the importance of early diagnosis and longitudinal multidisciplinary care to address the progressive and [variable] nature of this disorder,” the researchers wrote.
