Table 1

Language skills and cognition in this cohort with pathogenic missense/loss-of-function variants disrupting FOXP2

CaseAge at assessment (year range)Receptive languageExpressive languageIntellectual abilitiesLiteracy impairment
1a6–8Mild*Moderate†Moderate‡Severe††Average¶ PRI 100YY
1c30–32Average*Average†Average¶ PRI 100YY
1d60–62Average*Moderate†Average¶ MR 40YN
26–8Severe*Severe**Severe**Severe††Borderline‡‡ FSIQ 78YY
3a3–5Severe§§Severe§§Borderline¶¶ FSIQ 73YY
4a18–20Severe*Moderate†Mild*** FSIQ 67YY
4b18–20Moderate*Severe†Mild*** FSIQ 65YY
4c15–17Average*Average†Mild¶ FSIQ 62YY
56–8Severe§§Severe§§Average¶ PRI 94
Borderline¶ FSIQ 73
612–14Moderate†††Moderate†Severe‡Severe††Borderline¶ PRI 79YY
7a15–17Severe*Moderate†MildBelow average‡‡‡Average¶¶ MR 10YY
7b15–17Average*Moderate†Severe¶¶Below average‡‡‡Average¶¶ MR 8YY
8a36–38Average*Severe †Mild***Moderate*** MR 4NN
8b15–17Moderate*Severe†Severe¶¶Below average‡‡‡Average¶¶ MR 10NN
918–20Severe*Severe†Severe‡‡‡Severe¶¶ MR 2
Mild§§§ FSIQ 67
109–11Average§§§Average†Mild¶¶Below average‡‡‡Average¶¶ MR 17NN
11a39–41Average*Average†Average***Average‡‡‡Moderate*** MR 5NN
11b6–8Average§§§Severe†Average¶¶Severe‡‡‡Average¶¶¶ FSIQ 92YY
12a3–5Severe*Severe****Severe****Average¶¶¶ FSIQ 85NANA
16b9–11Mild§§Mild§§Borderline¶¶ FSIQ 78YY
  • Average=−1 < SD; mild=−1 to −1.5 SD; moderate= −1.5 to −2 SD; severe=< −2 SD. Below average=a qualitative descriptor based on the analysis of a transcribed conversation speech sample.

  • *Peabody Picture Vocabulary Test.59

  • †Test for Reception of Grammar, Second and German Editions.60 61

  • ‡Children’s Communication Checklist, Second Edition Semantics subdomain.61

  • §Wechsler Abbreviated Scale of Intelligence, Second Edition.62

  • ¶Clinical Evaluation of Language Fundamentals Preschool, Second Edition.63

  • **Children’s Communication Checklist, Second Edition syntax subdomain.

  • ††Kaufman Assessment Battery for Children, Second Edition.64

  • ‡‡Clinical Evaluation of Language Fundamentals, Fourth and Fifth Editions.65 66

  • §§Wechsler Intelligence Scale for Children, Fourth and Fifth Editions.67 68

  • ¶¶Wechsler Adult Intelligence Scale, Second and Fourth Editions.62 69

  • ***Receptive One-Word Picture Vocabulary Test, Fourth Edition,70

  • †††Analysis of transcribed conversation speech sample.

  • ‡‡‡Kaufman Assessment Battery for Children, Second Edition.64

  • §§§Snijders-Oomen Non-verbal Intelligence Test.71

  • ¶¶¶Schlichting Test for Language Production.

  • ****Communication and Symbolic Behaviour Scales Development Profile Infant-Toddler Checklist Understanding subdomain.72

  • ††††Communication and Symbolic Behaviour Scales Development Profile Infant-Toddler Checklist Words subdomain.

  • ‡‡‡‡Vineland Adaptive Behaviour Scales, Third Edition, Expressive and Receptive subdomain scaled scores.28

  • §§§§Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition.73

  • ¶¶¶¶Universal Non-verbal Intelligence Test, Second Edition.74

  • -, not assessed; FSIQ, Full-Scale Intelligence Quotient; MR, matrix reasoning; N, no; PRI, perceptual reasoning index; Y, yes.