De novo ARID1A Coffin-Siris syndrome with hypothyroidism and dyslipidemia: A case report and literature review

Table 2 Timeline of key clinical findings and patient history

Age	Event	Details/findings/actions
Birth (at 38 weeks via C-section)	Neonatal course	Birth weight: 2600 g; length: 50 cm; OFC: 33 cm; Apgar score 5/7/10; two cyanotic episodes with stridor (first 4 hours of life) aggravated by crying; wide nasal base, hypertelorism, high-arched palate eyelid capillary hemangioma; laryngoscopy: Laryngomalacia; NICU length of stay: 9 days
4 months	Failure to thrive	Weight and length < 3rd PC
5-6 months	Developmental delay	Delayed head control
8 months	Motor milestone	Unsupported sitting achieved
10 months	Motor milestone	Standing with support
13 months	Motor milestone	Assisted walking
23 months	Motor milestone	Independent walking
2 years, 7 months	Neurological evaluation	Developmental delay
2 years, 8 months	Molecular karyotype	46XY, 6p21.1 duplication
3 years	Therapies initiated	Speech, occupational and physical therapy were initiated
3 years, 7 months	Psychiatric evaluation	Developmental language disorder; severe expressive delay with high receptive skills; normal cognitive function; uneven skills profile
4 years, 2 months	Brain MRI	Short posterior corpus callosum
4 years, 4 months (first clinic visit)	Initial labs & treatment	TSH: 6.238 mIU/L with normal T3/T4 → subclinical hypothyroidism; low IGF-1 levels; hypercholesterolemia; T4 prescribed (20 μg/day)
4 years, 5 months	Genetic testing (WES)	De novo pathogenic ARID1A c.4102-1G>A → established CSS diagnosis; de novo pathogenic LDLR variant → familial hypercholesterolemia
5-7 years	Follow up	Euthyroid, improved IGF-1 levels; hypercholesterolemia addressed with diet; ongoing monitoring; freestyle exercise
Recent months (8 years)	Current status	Decline in growth velocity, pathologic GH stimulation test

C-section: Caesarian section; CSS: Coffin-Siris syndrome; GH: Growth hormone; IGF-1: Insulin growth factor 1; MRI: Magnetic resonance imaging; NICU: Neonatal intensive care unit; OFC: Occipitofrontal circumference; PC: Percentile; TSH: Thyroid stimulating hormone; WES: Whole exome sequencing.