Clinical Description
To date, 153 individuals have been reported with WDR62 primary microcephaly (WDR62-MCPH). The findings in these 153 individuals are summarized in Table 3 as Cohort 1 ‒ 17 affected individuals reported by Ruaud et al [2022] (including 1 previously reported by Nicholas et al [2010]); and Cohort 2 ‒ literature review of findings in 137 affected individuals compiled by Ruaud et al [2022].
Table 3.
WDR62 Primary Microcephaly: Frequency of Select Features by Cohort
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Feature | Cohort 1 [Ruaud et al 2022] 1 | Cohort 2 Literature review 2 |
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OFC | 17/17 3 | 72/137 4 |
Motor development | Normal: 6/17 w/independent walking < age 18 mos Delayed: 9/17 w/independent walking < age 3.5 yrs Nonambulatory: 2/17 at age 16 yrs
| 44/60 walk independently (age: 2-29 yrs) |
Language development |
| 44/59 able to talk (words to short sentences, age: 2-29 yrs) |
ID | Mild | 3/11 | NA |
Moderate | 4/11 | 2 individuals 5 |
Severe | 4/11 | NA |
Epilepsy | 12/17 | 41/109 |
Behavior | Behavior disorders: 10/16 6 | Behavior disorders: 21/24
Hyperkinesia: 4/21 Self-injury: 5/21 Aggressiveness: 15/21 Confusion: 2/21
|
Spasticity | 6/17 | 15/29 |
Ataxia | 7/17 (congenital: 6/7, progressive: 1/7) | 1/29 |
ID = intellectual disability; NA = not available; OFC = occipitofrontal circumference
- 1.
Ruaud et al [2022] described 17 individuals from 14 families newly diagnosed with WDR62 primary microcephaly. The Cohort 1 column reports the number of affected individuals for each feature over the number of individuals for whom data for that feature are available.
- 2.
Ruaud et al [2022] compiled a comprehensive literature review [Bilgüvar et al 2010, Nicholas et al 2010, Yu et al 2010, Bhat et al 2011, Kousar et al 2011, Murdock et al 2011, Bacino et al 2012, Farag et al 2013, Memon et al 2013, Sajid Hussain et al 2013, McDonell et al 2014, Poulton et al 2014, Rupp et al 2014, Banerjee et al 2016, Bastaki et al 2016, Wang et al 2018, Miyamoto et al 2017, Naseer et al 2017, Sgourdou et al 2017, Cherkaoui Jaouad et al 2018, Kvarnung et al 2018, McSherry et al 2018, Nardello et al 2018, Naseer et al 2019, Yi et al 2019, Zombor et al 2019, Rasool et al 2020] consisting of 137 individuals from 59 families previously diagnosed with WDR62 primary microcephaly. The Cohort 2 column reports the number of affected individuals with each feature over the number of individuals for whom data for that feature are available.
- 3.
Defined as 4 standard deviations (SD) (±1.5 SD) below the mean at last examination (mean age: 12 years, 4 months)
- 4.
Defined as 6.3 SD (±2.4 SD) below the mean at last examination (mean age: 12 years, 10 months)
- 5.
- 6.
Including hyperkinesia, aggressiveness, hypersociability, poor concentration, and disinhibition
Occipitofrontal circumference (OFC). In WDR62-MCPH, unlike other primary microcephalies, OFC may be within the normal range prenatally and at birth (mean: 2.4 SD [±1.046 SD] below the mean, range: 0.5 to 5 SD below the mean). The trajectory for growth of the OFC usually declines with age to reach a mean of 6.4 SD (±2.7 SD) below the mean in adulthood (range: 2 to 14 SD below the mean in Cohorts 1 and 2).
Growth. Intrauterine growth restriction is rare. Weight and length are usually normal at birth.
Neurologic findings. The ataxia reported in early childhood in six children spontaneously improved with age. Lower-extremity spasticity was present in two individuals.
In two other individuals, progressive cerebellar involvement was noted. In one individual, progressive motor decline associated with tremor and ataxia appeared in the second decade without cerebellar atrophy on brain MRI. In the other individual, ataxia manifesting as truncal hypotonia and inability to sit without support at age 20 years was associated with cerebellar atrophy on MRI.
Epilepsy. In Cohort 1:
Comparable information on epilepsy is not available for Cohort 2; however, it is notable that the proportion of individuals with severe cortical malformations in the two cohorts is similar (see Table 1).
Infantile spasms and focal and generalized seizures occurred mostly within the first two years. All types of generalized seizures were reported (tonic, clonic, atonic, myoclonic, and absences).
Developmental skills. Despite the high proportion of malformations of cortical development in this disorder, 15 of 17 individuals in Cohort 1 were able to walk, and 11 of 17 were able to speak at least a few words. Similar developmental skills were reported in Cohort 2.
Intellectual disability (ID). An assessment of 11 of 17 individuals in Cohort 1 using Wechsler scales determined that three had mild ID, four had moderate ID, and four had severe ID. Severe or moderate ID was observed in three of four individuals with severe cortical malformation and three of seven individuals without severe cortical malformation.
Individuals with mild-to-moderate ID had significant autonomy in daily life and good social interactions (based on Vineland Adaptive Behavior Scales). Regardless of the degree of ID, autonomy in daily life scores were higher than communication scores in affected individuals.