Story of a 15-year-old boy diagnosed with a heterozygous ACAN mutation with short stature and advanced bone age
Start of the Story
A boy was born at 39 weeks of gestation from healthy, nonconsanguineous parents.
He weighed 3.2kg (13th percentile) at birth.
He first visited a doctor when he was 15 years old with severe short stature.
At the time of the visit, his height was 149cm (under 3rd percentile), and his weight was 50.5kg (10-25th percentile). His childhood records also indicated that he had a growth delay from childhood.
Other than his short stature, he presented a mildly underdeveloped midface, frontal bossing, broad chest, short neck, ptosis (falling of the upper eyelid), brachydactyly (short fingers and toes), and low posterior hairline.
To observe his condition, the boy had to go through several examinations.
The first laboratory serum analysis revealed that his growth hormone and thyroid hormone levels were normal, showing no endocrine abnormalities.
However, his bone age and genital examination showed that he had reached his adult height. His bone age was 17-18 years compared to his actual age of 15 years 3months.
Failure of Diagnosis
To better understand the boy’s presenting features and where it came from, his family members had to be observed.
His father and grandfather also had short stature, and his father presented ptosis and short neck just like him. The father had records of pulmonary valve surgery and disc herniation treatment too.
Based on the facts, the boy had a RASopathy panel test, but the result was negative.
End of Their Diagnostic Odyssey
When he was 15 years and 6 months, he was tested for a whole-exome sequencing with 3billion to find his condition's genetic cause.
The test found a potentially pathogenic variant on his ACAN gene, which codes for protein Aggrecan, abundant in our cartilage.
His parents’ Sanger test results revealed that the genetic variant came from his father. It was not found in his mother or his siblings.
The boy's final diagnosis was 'Short Stature and Advanced Bone Age, with or Without Early-Onset Osteoarthritis and/or Osteochondritis Dissecans (SSOAOD).' To learn details about the disease, visit Rare Disease Series #11: SSOAOD.
Short stature and advanced bone age, with or without early-onset osteoarthritis and/or osteochondritis dissecans; SSOAOD (MIM# 165800)
- Possible treatments:
When the boy first visited the hospital to get diagnosed, he was already fully grown according to genital examination and bone age examination.
However, for the cases diagnosed earlier, the condition may be treated with drugs that delay sexual maturity (GnRH agonist) and growth hormone.