New research publication discusses the clinical phenotype of chromosome 9p13 deletion syndrome with tremor as a cardinal manifestation.
The distal deletion of chromosomal 9p has been well studied. However, proximal deletions of 9p are far less common, with only a few cases having been published. This study focuses on two boys with sporadic deletions involving 9p13 to help delineate the phenotype of such deletions.
The first patient at the age of 14 showed dolichocephaly (the head is longer than is expected to be), facial dysmorphism, mild synophrys, and a curved fifth finger. As a child he had cryptorchidism but that was surgically corrected. Occasionally he would have disruptive and oppositional behaviors (irresistible urges to pull hair from the scalp and grinding of the teeth). A neurological examination of the boy revealed abnormal speech and severe cognitive impairment. Coordination of the limbs, gait, and balance appeared preserved.
The second boy at the age of 12 showed moderate delay in his head circumference, height and weight. He had dolichocephaly, dysmorphic features, mild synophrys and a single palmar crease in the right hand. The patient also suffered from atopic dermatitis and asthma. The patient’s language was significantly delayed. He had a global delayed psychomotor development with attention-deficit and hyperactivity disorder (ADHD). Additionally, he had a continuous slight tremor, affecting only the upper limbs in a symmetrical way. The tremor was characterized mainly by high frequency and low amplitude and was exacerbated in situations of emotional tension or in the performance of tasks, many of which were impaired by it.
An 11.5 Mb deletion 9p13.3p11.2 spanning from 33,333,191 to 44,870,148 bp was identified in boy 1, while patient 2 carried a smaller deletion of about 2.8 Mb from 33,100,287 to 35,911,318.
Common features between previously reported cases and the two novel patients include: cognitive impairment/ developmental delay (in all patients), short stature (in 6 out of 7 patients), tremor (5/7), ADHD/ behavioral disorders (6/7), and mild genital anomalies (5/7 patients). This study outlined the clinical phenotype of chromosome 9p13 deletion syndrome with tremor as a cardinal manifestation.
Ferreira S.I. et al. “Tremor is a major feature of 9p13 deletion syndrome”. “Amer. J. Med. Genet.” 2020, v. 182 (11), 2694-2698.
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