Neurobehavioral and developmental profiles: genotype–phenotype correlations in individuals with Cornelia de Lange syndrome

Table 2 Mean age of meeting milestone (years) among the patients who reported meeting the milestone by the time of study participation. Standard deviation and range are provided in parentheses and brackets

	Center for disease control and prevention (CDC)	CdLS group [15]	NIPBL	SMC1A	Linear regression test results
	Developmental milestones (approximate time when a child reaches a milestone)		Mean age in years (standard deviation)[range]		β, t-value, p value	r²
Communication skill development			N = 17	N = 11
Social smile	2 Months	3 Months	0.95 (1.58)[0.5–6]	0.61(0.22)[0.5–1]	β = -0.12, t = 0.57, n.s	n.s
Single syllable utterance	–	–	1.22 (0.66)[1–3]	1.35 (0.98)[0.5–3]	β = -0.04, t = 0.15, n.s	n.s
Single word	15 Months	18 Months	1.50 (0.75)[1–3]	2.50 (1.70)[0.5–6]	β = 0.38, t = 1.43, n.s	n.s
Two word sentences	24 Months	4.5 Years	3.00 (1.87)[1–5]	3.00 (0.00)	β = -0.68, t = 6.05, p = 0.002	0.95
Motor development			N = 15	N = 10
Support own head	4 Months	–	0.50 (0.00)	0.55 (0.16)[0.5–1]	β = 0.25, t = 1.18, n.s	n.s
Sit	9 Months	12 Months	1.45 (1.01)[0.5–3]	1.62 (1.57)[0.5–5]	β = 0.05, t = 0.25, n.s	n.s
Crawl	–	–	2.12 (1.09)[0.5–3]	1.72 (0.90)[0.5–3]	β = -0.20, t = 0.86, n.s	n.s
Walk unassisted	18 Months	24 Months	3.10 (2.60)[1–10]	2.14 (1.06)[1–4]	β = 0.20, t = 0.78, n.s	n.s

The table above includes milestones recently published by the CDC, which was defined as the time when 75% or more children can complete the skill by the age. Of note, these milestones are not meant to be used as developmental screening measures alone as highlighted by CDC [21], these were included to provide a qualitative comparison of our sample in addition to the heterogeneous sample of patients with CdLS published in Kline et al. [15]. The linear regression test results outlined above stem from linear regressions with age at survey completion controlled, gene variant group (NIPBL, SMC1A) as a predictor, and the developmental milestone as the dependent variable. The response option of < 12 months were coded as 0.5. Regression coefficient (r²) represents the proportion of variance of the developmental milestone explained by both the age at study participation and gene mutation
n.s. not significant (p > 0.10)

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