Table 3.

Over-represented Gene Ontology categories in the list of proteins differentially abundant between children with small and normal head circumference (head circumference-for-age z-scores < −2 or ≥ −2) at birth, compared to the reference protein list.

Categories (Gene Ontology ID)	Ontology	Num. in reference lista	Num. in analyzed listb	Expected num.c	Fold enrichmentd	P-valuee
Structural constituent of cytoskeleton (GO:0005200)	MF	66	14	1.81	7.73	2.00 × 10−8
Actin cytoskeleton (GO:0015629)	CC	30	9	0.82	10.93	1.90 × 10−6
Intracellular (GO:0005622)	CC	191	15	5.24	2.86	8.13 × 10−4
Actin binding (GO:0003779)	MF	25	6	0.69	8.75	4.24 × 10−3
Cellular component morphogenesis (GO:0032989)	BP	64	8	1.76	4.55	3.52 × 10−2
Muscle contraction (GO:0006936)	BP	12	4	0.33	12.15	4.97 × 10−2

Abbreviations: BP, biological process; CC, cellular component; GO, gene ontology; HCZ, head circumference z-scores; MF, molecular function. An analyzed proteins list includes 25 proteins that are differentially abundant between children born with small head size (HCZ < −2) and children born with normal head size (HCZ ≥ −2) at birth (q < 0.05). A reference list includes 909 proteins which were mapped to annotation data (PANTHER GO-Slim) among all proteins detected and quantified by mass spectrometry (n = 982)⁵⁴. Categories are listed in increasing order of p-value. ^aThe number of proteins in the reference list that map to the particular annotation data category. ^bThe number of proteins in the analyzed list that map to the particular annotation data category. ^cThe number of proteins that would be expected in the analyzed list for the particular annotation data category, based on the reference list. ^dFold Enrichment of the proteins observed in the analyzed list over the expected number. ^eP-value determined by the binomial statistic after Bonferroni-correction for multiple testing⁵⁶.